I have believed since the early part of last season that Big Lou and the staff have differing opinions about whether he can carry the "extra" weight. When Kelly first arrived, Kelly was correct. He said that Big Lou couldn't make the necessary "work rate" [which is Kelly's code for number of snaps in a row, and number of snaps in game competition, at top power/effort function]. Kelly was seeing this in practice reps.
As Lou got with Longo's program, he both dropped the weight [some anyway] and Kelly saw his "work rate" rise. Still Kelly was skeptical but as that season went on he found that Lou could hang in there at high effort level beyond what he suspected. Last year seemed to max this dichotomy out: Lou gaining weight, but still functioning at high octane level. So the staff "looked the other way", and Kelly made jokes about Lou's "mystery weight" in press conferences just as Lou was attracting national attention as NFL ready Nose Tackle. [and Manti calling him MVP].
My guess is that Lou was poorly conditioned when he arrived and in his redshirt year, but Longo Beach changed that. That remains changed and the re-gained weight isn't quite the same weight, but also Lou is cardiovascularly more The Beast now. The bottom line is that Big Lou is a physical freak, who defeats Kelly's statistical tables, and so the staff will just shake their heads and let him play at 350.
Tuitt, beast that HE is, may not be quite the same situation, and really need to keep the weight down. Tuitt is Power & Speed. Big Lou is Power & Quickness. Weight carriage may play differently.