If some people received that text they'd respond with either verbal abuse (but written if it's a text back) or some kind of more polite, but still negative, opinion of him. So if he doesn't want to risk receiving these type of messages, the best thing for him is to not send the text that may generate them and to instead detete and block, effectively ghosting the other person. He has the right to do what is best for him. He doesn't owe you anything.
If he was a less selfish and more decent person he'd take your feelings into account but then, if he was that person, he'd also have checked with you before sleeping with you that you were fine with a casual thing because that's all he wanted. If he cared about others he wouldn't want to risk hurting them.
Selfish people care more about themselves and getting their own needs and wants met than about the other person and their needs and wants. Selfish people aren't going to be upfront and totally honest, they may even lie, because that's what gets the best outcome for them and they don't particularly care about how it affects the other person. People don't owe you decency, they have the right to be selfish. You have the right to choose not to have them in your life.
You need to stop judging people by your own standards and making the assumption they're like you. Other people aren't you. They have their own values and standards and part of dating is getting to know what these are, so you can decide if you want to be involved with the person.
If you want to have sex for the sake of having sex and can consider every time nothing more than a bit of fun for a short time, attaching no more meaning to it than that even if it happens repeatedly with the same person, then great. But if you can't, if you think someone having sex with you means anything other than they wanted to have sex and you agreed, then you risk getting hurt because you're getting emotionally attached and attributing meaning to the situation that isn't there in reality only in your imagination.
If this is you, then you can't enjoy casual sex, even though you may enjoy the sex, because you don't enjoy the emotional turmoil you experience alongside it. By taking part in casual sex you're literally giving yourself emotional torture. Why would you do that to yourself? Stop. Be kind to yourself and don't put yourself through this.