The inverse: ensure companies that are already working with companies are not leaving them for illegitimate reasons.
Could a be a “facts and circumstances” type of legislation similar to the IRS. Many IRS rules go back to the “facts and circumstances” of a particular case to evaluate all the nuances relating to it.
What "facts and circumstances" are we interested in? Your original post mentioned ending business relationships due to political stances. Did you mean the political stance of the advertisers, the platform hosting ads, some third party or parties, a combination of the above, or something I've missed?
Look up “no duty to deal”.