I would say, “Yes.” His book “Infiltration” accuses every Pope from Pius 12th to Pope Francis of grave errors on doctrine and discipline, and accuses Vatican II of teaching heresy. A heretical Pope cannot be valid. So, having accused the Council and the successive Popes before, during, and after the Council of heresy, Marshall is left with only two possible positions. Either these Popes and this Council were valid, or they were invalid.
1. invalid leaves Marshall in a state of Sedevacantism – the heretical Popes and the heretical Council were not valid, and so no valid Pope or valid Council has gone astray, and the Church remains indefectible. Invalid Popes (antipopes) and invalid Councils are not a defection of the Church.
2. valid leaves Marshall in a state of heresy and schism – refusing submission to valid Popes and a valid Council is schism, and accusing valid Popes and a valid Council of going far astray from the true faith is a denial of the dogma of the indefectibility of the Church, which is heresy. Also, the First Vatican Council taught the dogma of the never failing faith of the Pope, so accusing a valid Pope of grave failures of faith, such as heresy or idolatry, implies a rejection of that dogma as well.
From my point of view, all these Popes and the Councils (Vatican I and II) were valid, and therefore, Dr. Taylor Marshall is a heretic and schismatic for rejecting their teachings and authority. But as he states his own position, he can only be a sedevacantist, for his accusations imply that these Popes and the Council must be invalid. He cannot possibly hold them all to be valid and reject their teachings and authority as extensively as he does.
This is the problem with the current papal accusers. They imply necessarily that Vatican II and Pope Francis, and really all the Popes who supported Vatican II, are invalid. They can’t claim that these Popes and the Council are valid, and yet erred so extensively as is claimed, as this could be an admission, on their part, of their own heresy of rejecting the indefectibility of the Church and of open schism. If Pope Francis is valid, you may not “recognize and resist” for that is nothing but schism. You can only resist an antipope, so you have to find some way to conclude that Francis in invalid, such as an invalid election, or loss of validity due to sins against faith.