Rooney made his case on The Wayne Rooney Show, drawing on his own experience of being left out by Sir Alex Ferguson for a similar reason at the end of his Old Trafford tenure.
"I find it sad at the end of what he's done and what he's achieved at Liverpool. It's not the point for him to come out and aim another dig at Slot. He wants to play heavy metal football, so he's basically saying he wants Jurgen Klopp football. Now I don't think Mo Salah can cope with that type of football any more. I think his legs have gone to play at that high tempo and high intensity."
He was direct about what he would do in Slot's position.
"If I was Arne Slot, I'd have him nowhere near the stadium in the last game. I had it with Alex Ferguson. I had a disagreement and fallout and at Alex Ferguson's last game at Old Trafford, he left me out of the squad for that reason. That's your manager. You can't publicly disrespect him twice the way he has and get away with it."
Rooney also argued Salah's social media post was partly self-serving, pointing to a season that has seen the 33-year-old score 12 times in 40 games after netting 29 Premier League goals in the title-winning campaign last term.
"I think Salah's trying to vindicate himself and make himself feel better because he's had a very poor season. He's been very selfish in what he's done. He's almost dropped the grenade and said he doesn't trust and believe in Arne Slot and almost thrown his team-mates who are going to be there next season and let them deal with that."
Rooney said he is split on whether Slot himself should face consequences, acknowledging that some Liverpool players appear to have stopped trying.
"I'm quite split on should he go or should he stay because he won the league last season. I think he deserves a bit more time. I don't feel right or good saying this, but some players look like they've downed tools and that's a big problem for the manager."
Liverpool sit fifth with one match remaining and need a result against Brentford to guarantee Champions League football next season.