This tactic will only work if Mozilla doesn't want to bring queer people along with them — an open web for _most_ people, but some people aren't welcome to join in.
Making tools and services for public use is always political, and by tacitly endorsing discrimination against queer people, Mozilla would have been taking a stance that would have tarnished their reputation with a lot of potential contributors — just look at what's happening with Disney right now.
On the other hand, it might have been possible for Mozilla to retain Brendan's services without alienating a good fraction of their user base, with a suitably well-thought-through response:
- acknowledge Brendan's personal political donations
- affirm that Mozilla's position is on the side of diversity and inclusivity
- publicly describe the robust grievance/disciplinary/safeguarding procedure that any contributor would face if they did discriminate unfairly against other contributors (while stating clearly that this procedure has never been needed for Brendan, so any concerns at this stage are hypothetical)
- reiterate Brendan's technical credentials
I think the mistake Mozilla made was assuming that a high-profile leader's personal political position would always reflect on Mozilla; whereas I think it may have been possible to separate the two — as long as everyone's able to behave as though they respect each other.