Ruffian rogue sneak attacking with martial weapons through feats?

[Miraklu]

I got a suggestion from someone, so that the Ruffian Rogue, who can sneak attack with only simple weapon which has a damage die of d8 or lesser, could potentially do that with martial weapon.
the Weapon Familiarity feats, be it gnome, dwarven or elven give oyu proficiency in a select amount of weapons and:
"For the purpose of determining your proficiency, martial (...) weapons are simple weapons."
now I am unsure if that counts, for one if you count martial weapons as simple, then it technically would work for the ruffians sneak attack (as long as the damage die is a d8 or less), but the "for the purpose of (...) proficiency" lets me pause on that, because that sounds exclusivly for proficiency and not for "the purpose of class features and abilities"
So can anyone help me clarify if weapon familiarty feats would give a ruffian rogue the ability to sneak attack with a select amount of martial weapons or not and it just doesn't effect each other?

[Taja the Barbarian]

No, the general interpretation has been that treating a weapon as 'simple' for proficiency purposes does not actually make it 'simple' for any other purpose (like a Ruffian's sneak attack).

[HammerJack]

With examples like Elven Weapon familiarity that use the language in the OP, Ruffians absolutely does not allow sneak attack.

Now, there are some weapon familiarity feats, like Orc Weapon Familiarity that instead say "For you, martial orc weapons are simple weapons, and advanced orc weapons are martial weapons." These would work, though I suspect those feats will eventually see errata to correct them to being "for purposes of proficiency."

[Miraklu]

Thank you for the answer, and I am not surprised that it wouldn't work. It would be very broken to restrict the usage of sneak attack to finesse or agile weapons and with ruffian to simple weapons, just then to have a quite easy accessible feat to just get around it entirely. It would be kind of.....not saying broken but very unbalanced
but the orc weapon familiarity feat is weird, I haven't noticed it, but it indeed works diffrent. And all those weapon familiarity feats came in with the Core rulebooks so I am very surprised that this was mistake, but it also wouldn't make much sense to make that feat work diffrent then the other similiar feats