This is a completely false argument. I get to heaven the same way that someone who happened to die during any other papal interregnum would get to heaven. Even if the See isn't currently occupied, one maintains a state of submission to the Roman Pontiff. Similarly, if anyone died during the Great Schism while a subject of one of the Antipopes, he too could be saved. Why? Because the submission required is normally both formal and material, but in the case of a vacant See (interregnum) or material error regarding the identity of the true pope (Great Schism), the formal submission remains even if the material submission is broken.
Why do people bring in the GWS as a reference I do not know. We have one pope, not two, three or more, only one. There is no comparison between today and the GWS. Today, there is no confusion as to who the pope is, the confusion that reigns within some peoples heads these days, is who isn't the pope.
To say adherence to the dogma is a false argument, is to say our eternal God the Holy Ghost, in the year 1302, did not foresee today's crisis when He perfectly worded the dogma. So do not say it is a false argument. It is at least as pertinent today as it always was. That is dogma.
The sedes make the dogma irrelevant as this suits their opinion to do so, they claim it does not apply to this crisis, because in this case, the pope is a heretic so he is not the pope so the dogma cannot apply. As if the Holy Ghost forgot to add that little exception in there. Yes some of these same sedes will argue correctly that the dogma regarding the sacrament of baptism applies always, even for infants.
The sedes have allowed themselves to be led into a church without a pope, more importantly, a church that has no chance of ever having a pope. Their fake interregnum is, by design, forever.