I never said I personally ruled out cis folks??? Never thought I would have to say this, but wow okay here it goes. While I'm not keen on dating other trans people, I haven't shut myself off to the possibility. I can understand why they would want to avoid dating a cis person, too. Yes, people can be understanding or open to learning, but you also need to remember that being a trans person in a world that's ultimately hostile towards you is unnerving. You take a big gamble by coming out to someone or by putting yourself on the dating market. Someone can be kind to your face, hell, maybe you have a decent relationship. And then it goes sour for whatever reason.
That person holds a very dangerous piece of information about you in their hands. Someone with integrity would let go and keep your personal details to themselves, but this is still a person we're talking about. People are flawed and can choose to do incredibly messed up things if they feel they've been wronged. When emotionally wounded, humans will react with venom. Knowing they have something against the person that hurt them, they will likely choose to use this information to "get back" at their ex, etc. It seems like harmless relationship drama until the trans person is assaulted or - god forbid - killed because that information fell into the wrong hands.
Of course not all cis people are like that, and I've seen this kind of situation happen between trans couples as well, but it's a very valid fear and often the reason why a trans person will go out of their way to avoid romantic relationships with cis people. Sometimes it's just easier to not have to ~explain~ or to educate someone. Educating people is exhausting. If you don't have to spend a lot of time being the trans poster child, it can be better for your mental well being and promote a healthy relationship.
I don't take issue with someone wanting to clean up their dating pool to feel safer. Not all cis people are a threat or dangerous, but again, I understand why other trans people would want to avoid entangling themselves in relationships with them if they can.
That being said, I also find it equally unhealthy to only seek out someone because they're trans or cis(this is also directed at cis people who straight up chase or avoid trans people). You strip away the person beneath the label and avoid looking at who they are on the basis that "[cis/trans] people are more attractive/safer/better people to me" and that is not fair to the other party. Ultimately, you'll date who you want to date, but I still find the way people act when they're looking for a partner to be unsettling. It screams a lot about a person if they will go out of their way to say "TRANS/CIS PEOPLE ONLY".