You really think Kumail has nothing better to do with his summer than tell Chris Carter, Glen Morgan, James Wong and Darin Morgan "what lines not to step over"? Or that he would even WANT to?
Fox has something called "standards and practices" (or maybe it's not called that anymore- but it still exists!) to do exactly that. They will be making all kinds of "helpful suggestions" (one or two of which may even actually be helpful). They are also way more down on what's currently fashionable, and acceptable, with their target 18-34 demographics, than a gen xer like Kumail could ever be.
Are you implying that because Kumail has a Muslim looking name and brownish skin, his involvement with The X-Files would be undeserving of a major guest role, and could only ever take the form of "PC police"? That's a really fucking stupid suggestion.
Personally I think Darin Morgan or Glen Morgan, since he seems to have hung out a fair amount with both, have written him some kind of role. It may not be a huge, character-name-in-the-episode-title role (Kumail might not even have time for that) but it will not be some boring little role anybody from a casting couch could've played. However, I only think that he has a role because his own words have suggested that. And if he does have a role, rest assured, it will be an acting or maybe even a writing role- those are the things Kumail does, as a comedian. He is not a standards-and-practices person- that's not his job. As for promiting The X-Files, he does that in his spare time, but they don't need to pay him to do that, and if they did pay him, it would stop meaning so much that he loves The X-Files.
ps. Kumail is not "a representation of all of us." sure we relate to him, maybe more than any other X-Files fan or reviewer ever. this does not make his views on The X-Files (or indeed anything else) representative of "all of us." even if you are South Asian, the idea that Kumail should be expected to always represent your positions and outlook on everything is absurd. This is a dude who went to college in some Iowa town known for tipping cows and then became a professional comedian who is in an HBO hit and hangs out with all our favorite XF people. How many of us (of whatever background) led lives are like that?
Maybe the reason fans on here hounded Kumail so much he gave up the podcast had a lot to do with fans' mistaken view that Kumail is somehow responsible to "represent" everyone else.