No true Scotsman or fallacy fallacy

People who claim to be “ex-homosexuals” were never homosexuals to begin with. 

I’ve heard this when discussing the topic of homosexuality and the ideas behind the subject of one being able to change their sexuality. The claim itself in some discussions has been made that such a claim represents in a sense a no true Scotsman akin to something along the lines of “ex-Christian’s were never real Christians to begin with.” I don’t know some part of such an argument against the claim feels like a combination of the fallacy fallacy built on the foundation of a false equivalence. Thoughts? 

Yes, certainly can be a no true scotsman . The problem is, nobody can make that claim - not really even the person who converted. Human behavior is complex and vague labels don't map well with behaviors. Many "ex-homosexuals" are bisexual, and just choose to stay with partners of the opposite gender. If they had sex with someone of the same gender and enjoyed it, it is difficult to claim in any sense of the word that they weren't really gay to begin with. This is more unreasonable rhetoric than anything else.

The proposition: People who claim to be “ex-homosexuals” were never homosexuals to begin with. 

Start the analysis by defining the operative term. What is a homosexual?

The most essential function of a definition is clarity of thought because it allows us to know what we are talking about. Beyond that, if we are in a discussion, all must agree to use the same definition in the forum. Otherwise, discussion is impossible because the participants will talk past each other. There are technical rules for definition, but here are the basic rules.

Definitions are contextual. For example, the word“fast.” To go fast is different than to hold fast. A definition identifies the precise components of a “thing” — the thing under discussion.

Components must be coherent and understandable. This means they must be internally consistent. No part of the definition may contain a contradictory concept or term that invalidates the concept being defined. 

And it cannot be circular. That is, one may not use the term being defined as the definition. Lastly, the definition must be literal, not a metaphor or a parable.

When people are in a discussion, and one presents a proposition, unless it is  already agreed upon, the propounder carries the burden of proof to substantiate the proposition. This rule of logic has been around since Aristotle, or maybe Thales. 

I think it is obvious that unless one has evidence to believe something, there is no basis upon which to believe it. Hitchens’s razor says, “What may be asserted without evidence, may be dismissed without evidence.” Carl Sagan added the Sagan standard: “extraordinary claims require extraordinary evidence.”

So, when someone presents a proposition without evidence, the proper response is not to believe it, point out the lack of evidence for the proposition, and ask the propounder to provide some evidence.

If evidence is forthcoming, then the burden of proof shifts to you. You can accept the evidence, or if you do not find the evidence convincing, it is your burden to explain why.

In other words, you are a long way from analyzing the proposition.