Indestructable UZO?

Just had this hit me a moment ago. Made me go "Hmmmmm,". How is it that your watchtower can be complete cheese, yet the UZO is always functional? I can't ever recall it being unuseable. You'd think, considering it's pedestal-mounted out there in the open that anything that trashed the watchtower badly would also take out that, too. Granted, while the UZO optics themselves were stored below when not used the pedestal mounting was still in the open and vulverable, yes?

Anyway, just a 'hmmmmm' moment I guess.