Disregarding the limitations of any medium, the core question here is "should a content creator intrinsically have the right to share at their discretion or not"?
That is, if a creator is sharing something they made, should they or shouldn't they have the right to choose who they share it with?
(again, forget the practicalities of sharing stuff for free on the internet for a moment, this is about a general principle)
second question: is a content creator obliged to have a valid and generally accepted reason for choosing not to share something with someone?
The answer to the first for me is yes, and the answer to the second is no. It's their content. They can do whatever the hell they wish with it. And with thousands upon thousands of mods available to you unless you are perceived as an asshat by the majority of content creators which really takes a lot of effort, and tens of thousands if not millions of content consumers, I think the Nexus will be fine, and I don't think that is your primary concern but an attempt to shore up a rather weak argument.
By the way, content creators can't block you unless you comment on their mods - so if you feel your comments put you at severe risk of being blocked (and don't feel a little introspection might be beneficial at that point), then perhaps reconsider clicking that post button?