In conversation with Sky Sports, Merson said: "I'm on Mo Salah's side. I think he's gotten too much stick. Maybe he shouldn't have done what he did, but he's a human being.
"He's a winner. He's a legend. The figures he's put up on the wing - goals and assists - is off the charts. We'll never see that again in my opinion. All he's done is say he wants to play football. He's got the hump because he's not playing. How could you be slaughtered for that?
"There are other players in the team that could've been dropped and he's probably thinking 'We're not very good and I'm not playing'. I just think it's wrong. Liverpool wouldn't have won anything if it wasn't for Mo Salah. You take away his goals and assists and I don't think there's any trophies in that cabinet for a while."
Salah ranks as Liverpool's third highest goal-scorer of all time, trailing only Ian Rush and Roger Hunt. His tally of 250 goals has helped deliver two Premier League titles, the Champions League, the FA Cup, the Club World Cup and two League Cups for the Reds.
Last season, he produced one of the finest individual campaigns in English football history, recording 34 goals and 23 assists across 52 appearances for Slot's side.
This term, he has managed just five goals and three assists in 19 outings across all competitions, a modest return by his lofty standards. Nevertheless, Merson reckons he should be backed to recapture the form which made him so lethal last season.
The Sky Sports pundit said: "He's not the only one who has been playing poorly. Mo Salah can score from anywhere. He's the best worst player. Some days he is the best player you've ever seen and others you think, 'Really - what's the hype?'".
"He can be having the worst game ever but it never affects him. He can always pop up. As a manager, when you're struggling, do you drop your best player? That's where I think he's got the hump and he's just come out and been honest."