Ego has nothing to do with it. An accurate reading of the Greek does.A pronoun is being modified here, not a noun. Also if μεθ’ ὑμῶν is being “added to” εἰς τὸν αἰῶνα then εἰς τὸν αἰῶνα is not standing alone, is it ? Stop trying to do the dirty work for Gryllus, which he is not willing to do so for himself; because he probably knows that he is wrong. A true profile in courage. He is willing to lead naive people like you astray in the process.. Don’t be a victim of his ego.
There is no “predicate nominative” here because nothing is in the nominative case after the Subject.