Bust most real-world news stories and other interesting claims of material fact (and even moreso, claims of things being good or bad) are not syllogisms where the major and minor premise are trivially verifiable and the conclusion either follows of logical necessity or not, but are, to the extent they can be framed as arguments, inductive arguments.

You are also wrong about what ad hominem is (there are plenty of counterarguments to a logical argument that are neither on point not ad honinem), but the bigger issue is that the subject here is mot a logical argument in th sense that would make your claim correct insofar as rejecting all counterarguments that do not falsify the argument by logical necessity.

Ad hominem is a much more specific kind of non-rational argument.

All other arguments, directed at the source of the argument, that don't address the argument itself, are ad hominems.

Their expectation even had a reasonable explanation: their previous encounters with the source (as they saw them).

Then their actual judgment was on the merits.

And even their credibility expectations were based on actual experience (as they interpreted those) with the target, not something irrelevant to credibility.

It is a good example of someone whose experiences might have prompted them to make an ad hominem attack, but who didn't. The opposite of making such an attack if there is one.

Kudos that OP actually read it, but that doesn’t change “I thought the argument was weak because of who made it”