If he endorsed Baptismal Regeneration, then Calvinist Predestination most certainly did not have "a real hold on the guy". Calvinist Predestination admits zero incorporation of human works (even including the divinely-ordained sacraments of Baptism and Communion) in the ordination of the Divine Election of Predestination. To advocate a theory of Baptismal Regeneration placed this fellow in frank opposition to the Calvinist doctrine of Predestination.
So neither he, nor you, would be in the "good company" of Foxe's Book of Martyrs. Most of those hallowed saints died in defense of the Calvinist doctrine of Predestination. Realize that the fundamental reason why the Reformers broke communion with Rome was over the doctrine of Absolute Predestination. That was the fundamental doctrine which Foxe's Martyrs were dying for!!
The Reformation was fought, first and foremost, because mighty Men of God realized that if one honestly inquired what the Bible taught on the subject of Predestination... the only doctrine which one could admit as Biblical was the Calvinist doctrine thereof.
If not for Calvinist Predestination, we'd all be Romanists. At a fundamental level, that was what the Reformation was about. It was the only Doctrine which justified breaking communion with Rome. Why? Because it concerned the nature of Grace itself... the very heart of the Gospel. IF and only IF Rome had gotten THAT wrong -- and had strayed from preaching the Biblical doctrine of Absolute Predestination -- was the Reformation justified. Every other "offense" of Rome was an ecclesial offense (offenses concerning the proper government of the Church) which could be handled within the Church without breaking communion. Only the doctrine of Predestination presented an insurmountable disagreement between Rome and the Reformers... and justified the necessity of a Break in Communion.
Those who disagree with the Calvinist doctrine of Predestination have no ecclesiologically valid reason to be out of communion with Rome.
If you do not know this, you've got a lot to learn (I say in complete and charitable honesty).