I've never been gay or bi, and I've never used Grindr, but I have held government security clearances for almost 40 years. It's a lot different today than it was back then. Early on, I knew several people who had "experimented" in college, and they were denied clearances. (Actually the government never officially denied them because that would require an explanation of the criteria used for the denial. Instead, it was perpetually "pending".) Anyway, the basis for their denial was the potential for blackmail, which is a serious national security threat. Sometime within the past 25-30 years, they seem to have revised their policies so gay/bi people can get cleared, as long as they are open about it.