nah, they're likely removable in case of repairs. and if there's a bolt, then you can likely get them off somehow. maybe try some penetrating oil, let it sit, and then try again. if it doesn't budge, a light tap on the wrench with a hammer (a cheap version of an impact driver!) might loosen it up.
i'm gonna assume you're turning left to loosen, even if it's upside down.
i've actually caught myself doing the opposite when bolts are at odd angles or i'm getting at them from a weird position.