Can a determinist conclude that he is a determinist?

Apparently the Rabbi,
The guy who is a determinist and disbelieves in free choice can indeed objectively come to the conclusion that he is a determinist, right? That doesn’t fall under the claim that a determinist cuts down the branch he is on.
The only thing is that he will never be able to substantiate it because any justification is circular. But whoever claims it will indeed remain an objective reality (according to him).