Probably because it is one of the few things from the 1983 code they find acceptable

Some (many?) SSPX priests are announcing from the pulpit that the Lenten fast consists of 2 days, just like the Novus Ordo clergy. That is not and never has been Catholic. The Lenten fast is 40 days long just like Our Lord fasted 40 days, not just two. I've been told that because I am over 59, I do not have to fast, but nevertheless, though I am now 68, I am in better shape that most 40 year old men, so, in thanksgiving to God I fast as one. I will also abstain from going on the internet except for business. Therefore, I will not even be looking at CI  except maybe on a Sunday.

I was taught long ago that the fast in the USA consists of one normal meal and two other small meals that do not in total both exceed the one main meal. I find that to not be much of a sacrifice so what I do in practice is 2 eggs in the morning, nothing all day, and the main meal at like 4pm. If at late night I am hungry, I will drink a lot of water and if it is not enough sometimes I have an apple and a small piece of cheese. The Church does not allow fasting on Sundays.  There are certain days when we are not allowed to eat meat and on all Fridays one can't eat meat, no big deal since we never eat meat of Fridays.

No big deal, so why do SSPX priests not teach the real fast? It's bad for business? They've dumbed down the faith for the influx of Novus Ordo's since covid?  Who cares why they do it, take care of yourselves, learn the faith yourself and do what is Catholic.

God Bless

Not my SSPX priest. He spent the whole sermon on Sunday explaining the differences between the Novus Ordo guidelines and the traditional guidelines. He denigrated the Novus Ordo guidelines. He exhorted everyone to follow the traditional fasting guidelines, which, by the way, can be found near the beginning of the Angelus Missal.

They're just being consistent here.  If the V2 papal claimants are legitimate popes, then they have the power to dispense from the fast, and so the SSPX cannot impose upon consciences under pain of mortal sin something which a legitimate pope has said isn't binding under pain of sin.  It all boils down to whether you accept the V2 popes as popes.  Heck, even simple parish priests could dispense individual faithful from fasting depending on their circuмstances.

Unfortunately, if we fast when it's not binding, there's one particular mortification lacking there, which is probably the most important one of all, mortification of the will.  It's commonly reported that even people who love seafood find it difficult to abstain from meat on Fridays.  People who think nothing of just eating one meal a day most of the time somehow find it difficult to fast on the days prescribed.  That's because it's one thing to do it because you feel like it and quite another because you are required to under obedience, and it is the will that is being mortified.

1) If you're a dogmatic sedevacantist, then these would be binding for you under pain of mortal sin.
2) If you're dogmatic R&R, then these would not be binding under pain of mortal sin.
3) If you're in doubt, then a doubtful law does not apply (lex dubia non obligat), so technically speaking you're not bound under pain of mortal sin either.

So it's really only the dogmatic sedevacantists who are bound under pain of mortal sin to keep the Traditional fast.

One would be foolish not to perform the Traditional fast, but only the Church can bind consciences, and that's one of my biggest beefs with some of the dogmatic types who go around excommunicating people.

Not my SSPX priest. He spent the whole sermon on Sunday explaining the differences between the Novus Ordo guidelines and the traditional guidelines. He denigrated the Novus Ordo guidelines. He exhorted everyone to follow the traditional fasting guidelines, which, by the way, can be found near the beginning of the Angelus Missal.

Again, there's a huge difference in deriding the NO guidelines, while promoting the traditional, and quite another to think you can bind consciences based on your personal opinion.  SSPX promotes dogmatic sedeplenism.  So, as far as SSPX are concerned, these men are undoubtedly popes and they can't bind consciences over and above a legitimate pope.  SSPX constantly want to have it both ways.

Oh, so one gains more merit when one acts under compulsion than when one acts with free will?

This is a common theme in most of the lives of the saints.

The "evangelical counsels" are voluntary. More merit. 

Uhhhh....yes, of course.  That's what we're talking about - poverty, chastity and obedience - as practiced due to a religious VOW (i.e. done by obedience).  All catholics can practice these virtues but the religious get more merit because they take vows and MUST practice them.

The lay person who chooses fasting for 40 days gains more merit than one who chooses not to.  The religious who fasts because of a lifelong vow has the most merit.  Fasting + lifelong obedience is > temporary fasting > no fasting.

It’s a 3 tier comparison.