He is confusing the situation in 1970 with the situation today.
Long story short, he is confusing the SSPX with the Catholic Church itself.
Yes, the SSPX is part of the Catholic Church, but so is any other lifeboat (independent chapel). The SSPX is just the huge Wal-mart of lifeboats, that's all. And like Wal-mart, they like to put the little guy (independent chapels) out of business so they can get ever bigger, make more money, and take over more and more "territory".
In the early 1970's, when my mom (for example) left the Novus Ordo for good -- before she had anything to replace it with, mind you -- she had some clear cut reasons. She was face with the full-blown Novus Ordo Mass, with the proverbial "dancing in the aisles". McFarland and others (including, quite ironically, my own mother!) point out that the SSPX and/or Bp. Fellay isn't this bad right now, so we have no similar justification to leave.
However, they are confusing
A) Leaving one's legitimate Parish, which has formal jurisdiction over all Catholics living in that area, under the local Bishop and ultimately the Pope.
and
B) Leaving a given lifeboat, saying "this one is sinking" or "this one is as good as sunk"
I would posit that it takes much less evidence, or much smaller problems, to justify B).
In some cases, such as in locations with 3 or 4 Traditional Mass options, you could leave a chapel because you didn't like the congregation, the choice of hymns, the architecture, or even the priest's accent! Now to be clear, I'm only saying it's ok to nitpick in this manner if you have other convenient choices for Mass. Some places have this luxury; most places do not.
But a lifeboat has no default jurisdiction over ANY Catholics. Not even those who live right next to the chapel. Not even if that chapel is awesome, professional, has 2 million in the bank, has been around for 30 years, seats 1000, and has a parish directory of 2000 souls! Or if it was "the only game in town" for 30+ years. That STILL doesn't make it synonymous with the Catholic Church, they don't get any "free", "bonus" or "default" jurisdiction just because they grew to X size, and they are still no more legitimate than a small group having Mass in a converted garage or warehouse. Juridically speaking, using any possible objective measure THAT MATTERS, they are equals!
Are you familiar with the Subsistit in debacle from Lumen Gentium (Vatican II docuмent)?
Traditional:
Church of Christ is (Latin est) the Catholic Church.
Vatican II, Lumen Gentium:
Church of Christ SUBSISTS IN the Catholic Church. (Implying the Church of Christ is LARGER than just the Catholic Church).
Well, this is heretical when applied to the Catholic Church. But I'll tell you what: The truth is that the Catholic Church subsists in the SSPX. It would be false to say "The Catholic Church is the SSPX".
It's downright scary when I talk to SSPX parishioners who have been frog-boiled for almost 6 years now. They are talking completely differently about the Crisis in the Church, Vatican II, the nature of the Traditional Movement, obedience, and every other topic.
One small example: An older lady we were good friends with now believes our Resistance chapel is "disobedient". She never had this position before. She attends an SSPX chapel every Sunday (which is STILL not regularized with Rome, at least not publicly or officially). How does that work? So we all have to follow this group (SSPX) just because they're so big? Finders keepers, King of the Mountain, first dibs takes all? No one else gets to "compete" with their organization? They get some kind of default jurisdiction over all the Traditional Faithful because "they got there first"?
This older lady friend must believe, deep down, that the SSPX is equivalent to the Catholic Church itself. She must believe that they have some (invisible) jurisdiction, which our little group doesn't have. How else could she charge us with being borderline schismatic, naughty, disobedient, etc.?
That's what some pro-Fellay and accordistas believe regarding emergency-supplied jurisdiction for Episcopal consecrations. I've spoken to one, who basically said as much! "There was a state of necessity in 1988, but the SSPX got there first. Now there's no more necessity. Too bad for you. Obey us (the SSPX) or be schismatic. Have a nice day."
That's ridiculous.