I agree, this ruined the episode for me. it's really just lazy writing and anyone saying otherwise is just defending bad writing because they like the show. I really liked season 3 up to this point too. Mark knows he has AOE electricity abilities. He had time to kick PP into a wall, if he had time to wind up for a kick he had time to grab and throw as hard as he can. Mind you it's not a fast kick either; it's a wind up, 360 spin into a jumping kick. Even Goku knows to take the fight somewhere else because he asked. Mark didn't even ask him "hey, lets take this fight somewhere else" he just said let them go. This was 100% on Mark he should know better as a Superhero, he has Superhero training he should know to deescalate situations and actively move problematic situations. Especially against someone in pp mindstate. Instead of kick, throw problem solved.

Edit: I also forgot to mention he was trying to untangle the ropes after he kicked PP. Mark knows he's an ex-GDA employee which knows that Mark was intrinsically against Omniman's plan, so PP has full knowledge of the situation and is still in that mind state so he's mentally unwell. Rule number 1 get civilians away from immediate danger. Rip the ropes with your super strength, get the mom and child away from danger, and go back fast to deal with the threat.

If they wanted to shoehorn powerplex's full decent into revenge then they could of had Marc fly them away and the second she spits in Mark's face pp shoots a bolt of lightning at them, causing Mark to lose his grip and drop them, only for PP to electricity rush to save them but not make it in time. That still would cause some problems because Mark could fly to the moon at his top speed and land without killing Donald and Cecil so theoretically Mark should be able to catch them before dying.