Assuming the leaders of WarPac had a collective stroke and let Gaddafi in, he'd be a major source of headaches since day one. Libya has been known to support and arm the IRA, something Britain considers a direct breach of its internal security. Furthermore, Libya would have constant issues and PR headaches with its neighbors that would make WarPac regret ever bringing him in.
Take for example, the Chadian conflict, which was ongoing at the time Libya hypothetically applies. Muammar would run wailing to WarPac to intervene the moment the war turns against him (if it hasn't already), and WarPac would point out he brought it upon himself by being an idiot and an asshole. He sulks, makes a proclamation to the effect of "We're leaving WarPac, nyah nyah" and then withdraws it when he draws the ire of the US.
Or how about the Lockerbie incident? Does the USSR insist on defending the lunatic who caused the incident?
Gaddafi has a habit of shooting off his mouth, doing something stupid, and then caving in when someone kicks his ass over it. Does the USSR really need an ally like that? They'd reach for any clause that would allow them to kick Libya out.
Plus, as has been pointed out, WarPac was clearly an Eastern European outfit, designed as a buffer against NATO. Reaching out into Africa would throw off its logistics and political setup. I mean, Cuba and Mongolia weren't admitted in, for example, neither was North Korea - then again, Kim Il Sung was just as nuts as Gaddafi.