I think that he is just too worn out. As it has been pointed out before, he has retreated further and further into a lethargic state, probably as a result from a combination of factors ranging from the effect of constant trolling to his extremely bad health practices along with an accentuation of his mental issues.
Old Chris raged and ranted partially because he still hoped that he would one day find a 'sweetheart' to 'build from the ground up', anger was a way of countering a world he saw as unfair but capable of being changed via magical thinking. Which is why we had Sonichu in the first place, it was not only his attempt at creating a universe in which things worked out better for him than real life, it was a way of impacting real life. Seen in that light it makes perfect sense why Sonichu himself, despite being the titular character, eventually gave way to Chris as the main character. The Sonichu franchise allowed him to both project a brighter future for himself, one in which the trolls are punished along with Manajerks, as it allowed him to retcon the present and the past to fit a more positive self-image. I suspect this was also why he did not get too bothered at finding out a potential sweetheart was in fact another troll as there would be other sweethearts.
In other words, back in the day Chris believed he had the power to change his life for the better and his fits of anger were also a way of expressing said power. But he has 'grown up', in the sense that he does no longer have what Freud termed 'omnipotence of thoughts', he knows that no amount of comic-writing will ever truly get him a girlfriend. His original content has petered out probably for this very reason (among others, I'm sure).
Ironically enough, I don't think he has abandoned this kind of mindset entirely. Instead of faith in his ability of mentally project changes unto the external world, he now thinks he can do something a bit alike- those subliminal youtube videos- to change his body and gain a new identity as a woman. The mechanism is not too different but there is a crucial shift from the world of others (the curse-hame-has, for example) to the realm of his bodily self.
This change from an outer universe to a more confined reality also accounts for his being more depressed and less expressive. He no longer wishes, hopes to, or has any real interest in actually making connections with others, his already superficial notions of what an emotional connection is, as described in the 'love quest' paradigm, have waned and almost disappeared. With the loss of even a simulacrum of attachment to others, his emotional life reaches a kind of stagnation or stasis. A state of comfortable numbness, if you will.
In a way, despite having 'grown up', in a sense (and I use the expression with great reservations and caveats), Chris seems to have become more like a child than ever. I suspect pre-Sonichu Chris was very much like we are seeing now (minus the gender issue), unfocused, trying to endear himself to his parents for treats and not too expressive of anything.
Of course he still has bursts of anger and I suspect these will become worse and more violent with time. Now that he has no outlet to express his more violent urges, his frustration bursts out in episodes like the attack on the poor game staff over the color of Sonic's arms, of all things.
While Chris tended to be all bark and no bite, I can now easily imagine him crossing the line into psychosis and going from lethargically mumbling to himself to stabbing someone.