I feel that is overreach by the state (and there are quite a few others), but I would also ask if boycotting is not violence then not using a specific pronoun would fall in the same category as the above -impolite but not violent.
As a teacher, your job is to educate in the subject, teach some social behaviors (civics0 and stay away from political indoctrination.
It isn't an overstep, but is probably just a weird method for compliance. The Export Administration Regulation is a US federal law that includes penalties for supporting boycotts of US trade partners and allies. Normally this is directed towards anti-Israel boycotts in the middle east where legislation in several countries prohibit trade with organizations that also trade with Israel. If a US entity adheres to that country's boycott by refusing business with Israel, then they are in a legally actionable position. I don't personally know how Texas may be notifying people about compliance requirements, but this is actually pretty standard language in many contracts involving export compliance sections.
As a teacher, your job is to educate in the subject, teach some social behaviors (civics0 and stay away from political indoctrination.