kapusta
“If a competent Orthodox Rabbi would say its ok to drive on Shabbos, then yes, it would be ok. Because what a real Rav says, even if its Halachically wrong, becomes Halachically correct, simply by him saying it. Same goes for short sleeves.”
If a Rabbi says something which is clearly against Halacha like its mutar to drive on shabbos then his competence goes out the window. You are competent until proven otherwise. Making wild irrational or extremely meikil psakim is valid reason for declaring a Rav incompetent. Not every Rav can give a Heter just because he knows a few simanim of shulchon aruch.