Donald is the outstanding player on that team (although Jalen Ramsey can make a case, as well), but that doesn't make him the most valuable. The Rams still have a pretty good defense even without Donald. I don't know who the Rams' backup QB is, but you're probably right that Goff being out would sway the line more than Ramsey or Donald being out. If Goff's backup proves himself to be competent, that might not be the case.
But yeah, I think it's absurd for anyone other than a QB to win Most Valuable Player. The only exception I can think of would be OJ Simpson in 1973, which is the type of anomaly that will never happen again. That year, Simpson had almost 2100 yards from scrimmage, while the Bills as a team passed for less than 1000 yards. He was their entire offense. Henry has nowhere near that sort of impact for the Titans, who have a good passing attack, as well.