Suarez would know that claiming that "all the church fathers" taught something, would mean it's infallible. +Bellarmine would also know this (as well as the other theologians who agreed with +Bellarmine). I find it hard to believe that this was Suarez' claim.
If his claim was "most" or "nearly all" then that means it's a speculation, which means that people can disagree.
I don't know what you're reading, because Suarez did not claim that all or most of the Church Fathers taught something, he said that
"the Fathers do not teach that excommunicates are placed outside the Church..." This is what he used to form his opinion. Suarez lived from 1548-1617.
St. Robert lived about the same time, from 1542-1621 and what he says disagrees with Suarez. To form his opinion, St. Robert used Scripture (Mat. 18:17), a canon in the Decree of Gratian (canon law) and reason.
That's a summary of what it says in that PDF.
If you read that attachment, it ends up not answering the question at all, but only gives good arguments from both sides. Essentially what it says is that either way, it is up to the Church. Nowhere does it say, imply or otherwise even suggest that priests and laypeople may decide the matter.