"For the last fifteen or more years the seminaries of the SSPX have not been giving the seminarians the doctrinal formation to combat the modern errors. Modernism and liberalism have been promoted in the seminaries."

Please provide evidence for this lack of doctrinal formation regarding modern errors in the seminary.  What are some examples of modernism and liberalism being promoted in the seminary.  This is a weighty charge and needs to be supported with evidence.

for good and honest business people need to figure out how to market a safe and reliable product.

This is difficult to provide, unless you have a 18-23 year old man willing to go "undercover" at one of the SSPX seminaries, "Project Veritas" style.

Most young men who enter the SSPX seminary in the US, for example, are pretty strong SSPX supporters, regardless of whether they are ordained or not. So even if they're just an "ex-seminarian", they still strongly support the SSPX, and aren't likely to speak to outsiders about their experience.

That having been said, I did speak with one man who attended the SSPX seminary in 2000 and then again many years later. The differences were shocking. I wish I could get an exact interview to post here.

When I first spoke with him, I reported some of it here on CathInfo. They were constantly pushing "The 3 D's" for example. Dependence, Delicacy, etc. They stopped teaching Theology in Latin. They started working very closely with Conciliar (Novus) bishops. The Modernism is plain to see.

https://www.cathinfo.com/sspx-resistance-news/neo-sspx-seminary-pushing-the-3-d's/

Ceasing to have a problem with Modernist bishops, the Modernist Vatican II, and the Modernist Conciliar Church should be the biggest red flag of all, that Modernism has entered the SSPX.

1. Why undercover?  Just ask what the curriculum is currently being taught.
2.  The gist of your reply is that you have no concrete evidence for the claim.  Rather, their relationship or lack thereof with the hierarchy is sort of negative proof that "modernism has entered the SSPX."  No, not exactly, that's a logical leap.  I get that there are real problems in the SSPX, but making such assertions without proof only hurts your credibility.  In fact, the effort to put your disagreement on a doctrinal level is an implicit admission that anything less wouldn't justify "resistance."  Hence, the claim that doctrinal errors, not practical foolishness, is the real problem.  But in realty, something as simple as human respect could bring down an entire organization.  The mere desire to want to be at peace with one's enemies when there is a battle to be fought could potentially spell disaster and that can occur without changing one iota of doctrine.  They have the unenviable task of at once admitting all bishops have legitimate authority while at the same time trying to justify disobedience to the same group of men who are destroying the Church.  When those who they recognize as a true authorities desire to communicate or work with them, it is a very delicate situation, no?  Have they gone too far?  I say yes, they have.  I believe Fr. Wegner and Bishop Fellay should be expelled.  Many priests in the SSPX believe the same thing.  But to place this at the feet of modernism is simply without foundation.        

Do tell...

While people endlessly squabble about the legitimacy of claimants to the See of Peter, the real issue is the undeniable fact that the entire institution which has its headquarters in Rome is clearly an impostor, no longer promoting the One True Faith but destroying the faith of hundreds of millions.  If the body is alien, so must be the head thereof.

"Is he the pope or isn't he?"  Better to ask, "Is that the Church or isn't it?"

If that THING is the Church and THIS is what the promises, protections and guidance of God amount to, they aren't worth a whole lot, are they?

For what it is worth, it is rather difficult to have an apostasy without actual apostates, whether de facto or de jure.

Well, I'm sure you've heard this before but if the entire hierarchy, the entire "official" Church is simply speaking a non-Catholic sect, this would seem to call into doubt other dogmas concerning the very nature of the Church.  The question is to what degree can a man ruin the Church and still retain a legal title to the name Catholic and membership within the Church?  From my reading of history it's quite a high degree depending on the circuмstances.  Many are indeed apostates and heretics who lay claim to authority.  There are many others who are not apostates or heretics but who can cause just as much harm.  

 Has SSPX succuмbed to New Church? Has it given in doctrinally? Has the society “capitulated?” Maybe, at some level, yes. But for me, the major failures of the organization are its moral ones. Church Militant, since April, 2020, has carefully chronicled priest sex abuse and pedophile scandals within the organization since at least the 80s. CM discovers that SSPX hierarchy, just like the New Order, which it used to assault relentlessly, bends over backwards to hide Society scandals. They cover up for priests who commit such abuses. They reassign these priests to other parishes, where the same crimes are committed again. Just like New Church. SSPX hierarchy hides them out of the way in remote places, as does New Church. They rarely discipline or defrock priests that commit these heinous acts.
I wish that Bishop Williamson would address these issues in at least one of his future ECs. But I doubt that he will. Because for him, and for all you others, apparently, deviations from true Catholic doctrine, teaching and dogma occupy center stage, as, perhaps, they should under (normal) circuмstances. But how can you all seemingly look past that other 800 pound gorilla in the SSPX living room? Yes, the Conciliar Church is compromised doctrinally and morally. But now, so is the SSPX.