That's not how lawyers think. Microsoft's programmers were (are?) not allowed to read GPL code to rule out any doubt that they might be copy GPL code into the

That's not how lawyers think. Microsoft's programmers were (are?) not allowed to read GPL code to rule out any doubt that they might be copy GPL code into the codebase, even if only unconsciously. Lawyers are not just for suing they are also for covering your ass so there is no way you could lose if you are getting sued.