What the heck does morality have to do with someone being TG? Unless Morals are biological, there is no equating the two.
The closest you could come is if said person was TG-Gay - say a male to female but likes females - and then you could question the 'morality' of any relationship as much as you can question the 'morality' of any gay relationship. But whether the person is MtF or FtM has nothing to do with morality.
And by what basis do you say someone who is TG has no 'good morals'?
Except there ARE people who think Rape IS moral, that it is within their 'moral rights' to take what they want from women, regardless of permission. They are right to do with women what they want. Add to that, so they have no proper 'moral thinking' when it comes to rape, but if we ask this same rapist if he believes in say, pedophilia, and they vehemently say no, how are they now suddenly capable of moral thinking when they weren't before?
Rape isn't about morality mostly, it's about control, a person's control over another person.
That's why morality - what is right and wrong - is subjective, IMO. Even when the majority agree something is immoral, there will always be someone who think it is their moral right to do/believe/say otherwise.
If homosexuality is a sexual preference, and can't be cured.
Then
None consentual sex is also a sexual preference, and can't be cured.
And
pedophilia is a sexual preference, and can't be cured.
It's all wrong but they can't help themselves.