That's a Wilson, right? Yup, that wire is supposed to be used to ground the antenna.
I've never cut open one of them to see what the heck it might do but I'm also not sure what they're designed to be. I'd have assumed they would be electrically 1/4 wavelength but I suppose if they're 1/2 or 5/8 then the wire is part of the matching network.
I'd tape it to keep it from shorting to anything and try mounting and tuning without it to see what you get. If it will not tune up, try grounding it to see if it helps.