The developer is involved to the extent that they have to do what Sony says. The CEO of Arrowhead even tweeted that people should email Sony, referring to a Playstations own website where it stated that PSN is optional. Sony then quickly changed their web page to say it's sometimes required.
Yeah but it seems like they were not expecting this change just based on their responses on social media, and it looks like Sony didn't even "require it" until just recently. So I just wanted to know.
A change like this may warrant special exceptions to the refund rules. Steam has made exceptions for similar changes to games made after launch in the past.
That's true. Personally though, it not being optional for any amount of time just shows that there's no good argument to have it be mandatory in the first place.