Matthew

Loki destroying Harold doesn't prove him stronger. Remember Harold was fighting against Imu taking full control of him and wanting Loki to kill him to stop Imu from taking full control. I don't think Loki would have beat Harold if he fully fought him at that time. That's not to say he wouldn't do that now but not then.

I think he is a spy but not for the government. I think he is for Garp. After the events of God Valley in the Manga, I think Garp is in the Marines but closer related to the revolutionaries than we know. I think Kuzan helping to catch Garp has to do with this plan. Garp stayed with the Marines to help protect the small guys and keep them from getting to corrupt but he is definitely going to side against the world government when the war starts are he know the celestial dragons and elders are evil

Unless the theory is Ryuma was sent to the future, then this would create continuity issues as Ryuma died about 400 years before Thriller Bark. But why would Toki have sent him only 400 years in the future instead of the roughly 800 years she jumped or even further to the time Joyboy would return

This theory has way too many holes at this point. Oda could make it work if he wants to but the holes make believing it impossible imo

I suspected he would have this Haki as soon as he was shown meeting Luffy.

Luffy is going to have to learn the haki Joyboy left in Emet to defeat the elders and Imu and he needed someone to teach him. Now he has someone that can t2ach it to him or at least he can observe to figure it out like he did with his observation/ future sight