I think it is very bold of him to claim starting from zero would be slower. He has accrued so much hate that if he were to start one I can't see how it would turn out any different than truthsocial or if Biden started his own social media platform.

Although I do think it's doable if he somehow kept the fact that he is at the helm a trade secret as he gradually grew the userbase until reaching a certain critical mass and finally revealing that he's the owner.