Not at all. If, in BM's opinion, he had nothing more to give, and had reached the pinnacle of his career, then he did have no more potential. It's his opinion.
I respect each and every person's opinion. But when a claim is made I suggest they get the correct terminology that is required. I have given the CORRECT definition of the word "potential" if you wish to dispute said definition then so be it, but it isn't advisable.
Or perhaps I should work full time to stop me drinking in afternoons. I suggest both options as being viable.