I wouldn't put his situation into the same as Samarin's. At the last (or the last two) season, Samarin only had 4lz as his ultra-C's and the 4lz wasn't very stable either. Dima still has three types of quads in his arsenal. Among them, 4t and 4s are reliable, and the success rate of 4lz was decent. At the end of last season, he almost pulled out a 4 quad fs program in the RUSGPF. Considering he picked up 4s after 22 olympic season and regained 4lz only last season, it seems that his technical capabilities are still there or not peaked yet. In the past a few seasons, he always got to shape gradually and tended to do better in the second half of the season. This season, the knee injury prevented him from training at full capacity. Another factor is that adding the 4-th quad into his fs program seemed to me interfered his performance. Only he and his coaching staff can decide which makes better sense, 3 quads or 4 quads.
Obviously Dima got quite upset by the nationals results. But most likely it was more a spontaneous reaction as he is a sensitive and emotional person. It's not like nobody else wasn't struggling. Even the "younger" guys can't deliver consistently. It's pretty common among guys.
Also, Dima is a component skater and has a full package. He is the one who truly deserves the 2nd mark in the mountain of mushrooms. Whether it is fully awarded is another story.