I was reading through this sub's history and someone actually said that when they transition they will not socialize with transgender sex workers.

Not wanting to socialize with somone is not the same as hating someone. They are not necessarily the same thing, but it is possible they could be.

Whats wrong with them?

You're the one assuming something here. All you've given us is they won't associate with sex workers. There could be nothing wrong with them, or a lot wrong with them. But you are projecting "wrongness" onto them for not agreeing with you. Which I could argue is you doing the moral wrong here.

Why would you be transphobic to a fellow trans person?

The way this is worded it is not at all transphobia. If they said they would never hang out with any trans person, then it might be safe to assume they have internalized transphobia.

That said, I won't hang out with sex workers, neither cis nor trans. And possibly giving you my reasons will help you understand why others won't either.

I one, don't hang out with any criminal elements, and sex work is largely illegal. Thus it is an illegal career. That doesn't mean it should be illegal, it just is illegal. My moral compass steers clear of those who intentionally break the law. That doesn't mean I agree with the law, it just means I don't hang out with those who do, and that has nothing to do with with whether I like or hate you.

I don't think I classify as as a SWERF, because I do support sex workers and the legalization of sex worker, but I still personally hate the notion of sex work. The history of sex work is actually the history of sex slavery. I would wager a vast majority of all "sex workers" in history were actually sex slaves. I'm also against women/girls and others being forced into financial positions where they feel - based on socialization and/or society defining worth of a certain body - the only thing they have of value is their bodies and thus feel that's all they have to sell / give for an income. That's a societal level problem and not anything to do with the person in question.

Personally, I hate sex work itself. I don't hate sex workers. I have a very troubled past that involves a lot of sexual violations and rape. Which combined with my morals and views on how "sex work" evolved overtime into what we see today, makes it about impossible for me to be a sex workers friend. If you tell me you're a sex worker, then even if we were getting along as best friends, I would immediately end our friendship.

Fwiw, I've been everything from homeless to fired for being trans, and I've never had to break the law. I could have, many times. I definitely have a body that would make a lot of money with sex worker, and if I had I would have escaped the hells I was in a lot faster too. But it's against my ethical and moral compass. One thing I take great pride in is my integrity. I fall asleep everything single night in about 15 seconds. Insomina to me means waiting 3 or 4 minutes to fall asleep. I believe this is because my conscious is clear and that despite it all I still have my personal integrity. I highly value my personal integrity, and for me to personally do sex work would greatly damage that, and for me to be associated with criminal elements also makes it hard to sleep at night. To each their own, but I get to decide who is my own, and you would not be my own if you do sex work.

That said, I only want to hang out with people who are like me, and if you're a sex worker, then you're fundamentally not like me. It is no judgement upon you, and I will and would vote for your freedom to do so, nor does it mean I hate you either, but I do have the right to pick and choose my company based on my perosnality and who I deem compatible with me: sex workers, regardless if trans, are not compatible friends/ companions with me.