Depends what he’s calling “this scenario”. OP is specifically asking about developing T cells in the thymus. Those do occasionally bind with high affinity to the MHC/self peptide combination in the thymus, and those T cells are destroyed - it’s a normal part of T cell development, aimed at preventing autoimmunity (because if those T cells were allowed to survive and become mature, functional T cells, they could indeed cause autoimmunity - though there are further checks and balances even there).