I am a true villain, a villain to Molière or the commedia dell'arte." Sooo what's a fake villain and what's a true villain?
What did you use for the translation? A dictionary which gives the French term "faux" as "true" belongs in the fire or taken off line.
"Faux méchant" translates literally into English as "false baddy". When you lived in France for 16 years like I did, you can be a little certain about these things.
It could be an expression that has some kind of double-meaning. My best guess is that in this film Ben Salaad is an enemy but shouldn't be. A bit like: they spend much of the story fighting one another, only to discover at the end that they are actually on the same side.
Since Gad Elmaleh connects this to 17th century plays, I'll leave to a scholar of Molière or the commedia dell'arte to explain what it means.
The spoilery bit (or maybe not too spoilery since you've all been sure of it, except me) - the guy IS Sakharine.
In the original book, Sakharine could be seen as a "fake villain" since Tintin suspects him of stealing the model ship (at the beginning) or of stealing the parchments from the Bird brothers. In both cases, he turns out to be innocent.
Could be that that is Omar Ben Salaad's role in this story. These days, you have to tread carefully when depiction a Muslim villain.
Apparently Sakharine in the film is Red Rackham's descendant. Looking at the books, I can imagine the relationship being put down to their beards, which are similar, but Sakharine's nose is more hawk-like than Rackham's. This might even nullify the "descendants of Red Rackham" joke from the Treasure book.