There were two main (ugly and horribly flawed) rationalizations for this type of policy.
The first āreasonā is so tragically stupid that it's hard for people today to realize that people in the past actually believed ideas like this. It almost certainly had origins in religious and cultural biases and misanthropic tendencies tantamount to evil. The second rationale is insidious in a different way and is a perfect of example of how privacy and security can become conflated to the point of causing true harm to the very things they purportedly are meant to protect.
NOTE At the time the laws/policies discussed in this chapter were created/implemented/enforced, there were other terms used to describe any sexual activity that did not conform to heteronormative standards, typically unnatural acts and sodomy, when included in statutes or other written mandates.
The historical personnel trust model is based on some simple premises: institutional trust is linked to personal trust, personal trust is based on using past behavior to predict future action, and personal behavior outside the workplace (such as sexual activity) is linked to personal behavior in the workplace. For the institution to trust the individual for a particular job, the institution must learn and know about the person's behavior outside the workplace, in their personal life. That's the institution's perspective.
Generally, from the individual's perspective (instead of the institution's), we like to think of a person's home life and work life as two separate, distinct contexts: I act in accordance with my employer's needs during the hours I'm working, because that's what I'm getting paid for, but when I am not working, I am free to live my life in the manner I see fit, without my employer's oversight. I might wear a uniform in the workplace, but I take it off when I'm not working; I associate with colleagues and customers while I'm working, but I might have a totally different set of friends and acquaintances when I'm not working, and I might not interact with the workplace colleagues/customers until I'm back in the workplace.
In reality, this construct often breaks down in actual practice. Colleagues and customers share information about their nonwork activities in workplace discussions, and actions a person takes outside the workplace can seriously affect their employment, be it acquiring a college degree or running someone over with a car while driving drunk. Even so, we often like to think of ourselves as having a bifurcated existence.
In order for the dated trust model, which discriminated against gay people to have existed, the institution had to breach the employee's private lifeāsex is generally (with very, very few exceptions) an activity that happens outside the workplace. This intrusiveness was seen as necessary in order to ensure that the person placed in a position of trust by the institution was, indeed, trustworthy.
This, of course, makes absolutely no sense, when exposed to even the barest logical scrutiny. Were gay people subject to blackmail/coercion because of their same-gender sexual activity? Yesābut only because the institutional trust model created that situation. The person who is given employment or promotion only under the condition that they act in a prescribed manner (or, more to the point, do not act in a proscribed manner) is under the threat of losing something of value (a job, a promotion, etc.) if their unapproved behavior becomes known.