since we're onto the Handshake after the match what is the situatiion for the winning wrestler to go to the opponent's coaching corner and his opponent's coach is not there...(generally a father coaching their kid) that has "left the matside".

Sometimes coaches are running between matches and the handshake gets missed....but that's a no harm no foul situation since the wrestler-coach handshake is a courtesy, not a rule requirement.

I have only seen one situation where the handshake caused an issue and that was because the coach started berating the wrestler for something the coach did not like.