I fail to see how this was a "tough call". Please enlighten me.
I'm assuming for the sake of argument this is an SSPX chapel or something similar, not a Sedevacantist council.
Schism is formally defined as refusing to submit to the Roman pontiff or to be in communion with the members of the Church subject to him.
Let's assume for the sake of argument that this guy is, in fact, Catholic, but is a material heretic because he doesn't realize "Hebrew Catholicism" is heretical. But he's in good standing with the Catholic Church (even though he should be corrected.)
What's the justification for refusing the man communion in this case?