It is generally considered a bad idea to have blue lights on the front of your bike as in some places it is explicitly illegal and in others will get you unwanted attention. I read over those TX laws and saw nothing that forbid it. I also found lots of others online asking the same question but no real answers. If you are considering fighting this first step is obviously a local lawyer. I would think they could quickly tell you if this is legal or not as I doubt you are the first person to have this problem.
Other thing to consider is I don’t think local court judges sit around debating the various merits and legal precedents of each case. If they are in a grumpy mood or don’t like the look of you or your lawyer then bend over. It all depends on how important this is to you. I see fighting it as a risk of time & money but I don’t know what the odds are. I am curious to know how this turns out so please keep us informed.