It’s worth noting that Josh McDermitt said nothing specifically in regards to The Walking Dead or Eugene’s role in all this.
Why Josh McDermitt won’t get outright specific and confirm that’s what it’s about is unclear.
While it could be true that lots of people out there are inappropriately angry with his cameo role on Angie Tribeca, it’s safe to speculate that a majority of the toxicity is coming from Walking Dead.
It could be he’s under some contract stipulation that prohibits him from making disparaging remarks about fans of the show, or it could just be something as simple as him not wanting to give attention to a small minority of trolls who don’t deserve it.