Because it's part of a new trend to de facto ban stuff the governing party would like to ban despite it being theoretically constitutionally protected by creating new civil offences and encouraging vexatious litigants to file nuisance suits. In this case the outcome is, as the state which passed the bill intended, that homosexuals are being harassed out of their jobs.

Regarding the state circumventing constitutional protections to make references to the gender of their partner a potentially career-limting move for certain minorities as less problematic than a company adding suggestions to avoid gendered language as a [clunky] grammar checking feature of its software is a point of view, I guess....