The argument you make is that this has God saying "after thy enemies are thy footstool, no longer sit at my right hand."
Simply put, you imply that Matt 1:25 means that after the "till" things from the first half of the sentence must change. If they had no relations "till" the child was born, they must have had them afterwards. That is your argument.
Using that argument, after God made footstools, he doesn't want Jesus at his right hand.
SD
Case closed.