He doesn't know the consequences Caius will face if he goes home because Caius didn't tell him. Most likely, Palo found out from Dr. Martu and is now in the process of stopping him so that he can tell because Palo was there when he said that.
Well still, Caius knows better. Caius knows how he feels, he knows why he wants to go back, So that his mother wouldn’t have died for nothing.
Caius loves Koichi too much to burden him with what will happen to him in response to him sending him home
Well, Caius just burdened him more by not telling what was going to happen. Know Kouichi going to think that he killed the love of his life, and the lives of the titan people
Godamnit, what happened to “I don’t want anyone to die because of me”. Shit.