Whats all teh talk about the swimsuit??
Arnie spent his 20's and 30's in the 1970's and 80's...That was the swimsuit fashion at the time. People didn't ware billabong shorts then, at least in Europe they didn't. Everybody wore that. Its simply natural for him to revert to what he's used to. My dad, whos same generation as Arnie also wears this type of swimsuits. Its just a habit.
I bet when we all 50-something and keep wearing our bermuda shorts, the teens of those years will also find it funny.