Bi men who live straight lives with a wife and family are ridiculously common. The ability to blackmail those people is extremely valuable to certain state organizations.
It's entirely possible that even the ability to verify that a particular email address has a Grindr account may be enough to threaten a person with imprisonment or death in several countries I can think of off the top of my head.
Sodomy laws were still on the books - can you keep a clearance while openly breaking the law every time you and your partner sleep together?
That's what I have been told is the current policy in France. As long as you cannot be blackmailed with it, it is good.
A bi man with a wife and a family could very well be having sexual encounters with men once in a while with the agreement of his wife (who could well have her own stuff going on too) and it could be a very healthy thing in what is a fulfilling relationship for both parties.
They're not that common. The literature shows a bimodal straight/gay distribution of homosexual tendency in men and a more Gaussian distribution in women.
Seriously?
Surely the way someone identifies public doesn't necessarily match with reality.
If you are visible on Grindr, you have made a kind of public testimony.
So, you have reduced your blackmail risk - since you're already at least somewhat prepared for this information to be public.
Why is blackmail the risk that people on this page are going to, then, is my question. If you're willing to make a public statement then blackmail is lower risk, not higher risk.