It bothers me that Gambit blocked his own powers. As New Sun (weird name) he was at least a beta level mutant, with the ability to control time i.e. with his mastery of kinetic energy-> slow down or speed up time

No the New Sun had Omega level as he able to charge up even living beings and steal their kenetic energy preventing them from moving. In verly talk of but the New Sun did defeat the Dark Phoenix of his reality and could even traveled time, however the Witness in my opinion is another form of the New Sun were his power never flare out control and he came to harnessing all his power from charging up any object to steal the kenetic energy of time causing a portal to move bewteen realities, he as much survive Onslaught that a feat it self. Give he poor old man a healing factor and he be back to his younger years