Speaking on BBC Scrum V, Gwyn Jones laid into the England bad boy after his fondling incident with current Welsh skipper Alun Wyn Jones.
Marler escaped sanction for the first-half incident during a melee that went unnoticed by the match officials at the time. However it was revealed today that he was cited and will face repercussions.
There was no sympathy for Marler’s actions on Scrum V on Sunday night, with Gwyn Jones leading the criticism of the loosehead.
“I think it was an attempt of humour of some kind but I don’t think there’s any doubt that it was unacceptable to do what he did”, he said.
“I think this is another example of Joe Marler just showing his stupidity.
“I think he’s trying to cultivate this image of him as a rugby character, where it’s the Mohican haircut, or the words he used against Samson Lee, or the interviews he does.
“To me, the attempt of humour there was inappropriate and will get sanctioned. He’s nothing more than an egotistical narcissist – if they could ban him for being an idiot, they should, but I don’t know if they can.”
Marler’s England colleague Courtney Lawes will also face a disciplinary hearing on Thursday, having been cited for a dangerous tackle on Jones during Saturday’s 33-30 win at Twickenham.
Manu Tuilagi’s automatic hearing following a red card will also be held at the same time, with the centre also set to discover if he will be suspended.
Six Nations disciplinary chiefs confirmed Marler would face a hearing, charged with infringing laws on sportsmanship, with the Quins front-rower called into question over allegedly “twisting or squeezing genitals”.
Marler’s cryptic tweet of “B*******. Complete b*******,” while not directly attributed to anything, could easily be viewed negatively by the authorities.
Wales captain Jones was frustrated that no action was taken against Marler at the time of the incident.
“There’s a lot of footage that has been shown, it seems like a lot of supporters saw what happened,” said Jones.
“It’s very frustrating that we talk a lot about TMOs (television match officials) and footage reviews, yet there doesn’t seem to be a lot of it happening.”
England boss Eddie Jones lamented a clutch of refereeing calls in the aftermath of his side’s slender victory over the Welsh, but Tuilagi’s red card yields an automatic hearing.
The disciplinary panel are likely to take a dim view of head coach Jones’ criticism of match referee Ben O’Keefe, with the outspoken Australian claiming “at the end we were 13 against 16 and that’s hard”, and branding Tuilagi’s red card “absolute rubbish”.
Northampton flanker Lawes could also now face a ban too, should he be found guilty of a dangerous tackle.
– PA, additional reporting RugbyPass
Sign up to our mailing list here and we’ll keep you up to the minute with weekly updates from the world of rugby.