Why would it work? You think if you told the judge "nothing I can do, it says right here in my employee handbook that I'm not allowed to seek legal counsel without a public bidding period" they would say "wow, you really outsmarted us this time, nice job"? If part of your job involves breaking the law, then the law compels you to not do your job.

It seems like you're trying to hack in a domain that can't really be hacked, because it's not even very well defined. The spirit of the law is clear, I can't see any reason a judge would come down on your side of this. Prohibiting a bidding process does not restrict any of your rights.

I have no idea if it would work. As you state, it isn't very well-defined. I imagine it would eventually depend on a clarification of the phrase "your choice."