Old full contact american kickboxing was like this cause it only allowed kicking above waist making it a boxing style with kicks. Low kicks made the difference when facing thailands
Come how I haven't heard of this savateur, going to have to analyse all his fights, what wonderful aggressive technique with beautiful alternation. That said my favorite is probably still Francois Pennacchio for his work against Muay Thai and Kickboxing fighters. He set the standard for a hardened savate with superior defense without sacrificing technique.
Elite level savateurs did beat elite level Muay Thai boxers and kickboxers. But at the end of the day, it’s the person, not the style, that wins fights
this is where you are wrong. If the extend the leg it's to respect the rules of the SBF . now watch a SBF s Muay Thai fight (any rules you want, but best is Kick boxing) , and you'll see if it don't work .