Well, it's plausible he was being carefully selective with his wording intentionally, when he said, "The Terrigen Mists... they're also
possibly having some sort of effect on mutants." With that, I'm more inclined to subscribe to a theory which has already been posited by others, in where there may be another factor involved, that's been implemented by an as yet unknown third party. It's not hard to imagine the cloud being altered & tainted after the fact, with an unnatural contaminant of sorts, so that it would start adversely affecting the mutant population. By someone with a nefarious agenda perhaps, towards Inhumans, mutants, or both, that believes they'll somehow benefit by pitting the two subspecies against each other. And while I expect things will inevitably escalate to there's a violent confrontation between the two, I do hope that once the truth is revealed & the real culprit is exposed, they UNITE in force against their now common enemy... before
too much damage is done, to EITHER side!
Also, if you suspect I might've been speaking in code with all this, to both Marvel AND comic fandom alike... you'd be right on the
$!<Which by the way, literally speaking,
IS the real enemy.