If somebody puts it on the Internet in public, by definition that means if you have a computer, you can see it.
If you can see it, you can make a copy of it.
If you can make a copy of it, you can put that copy on your own computer.
If you have it on your own computer, you can order that computer to run any computer program on it, including training an AI.
If you don’t want people to use the information you post in a certain way, the best way is to not post it at all.
The second best way is to post it in a private place, that is only accessible by a small number of humans, tell them you don’t want them to post it in a public place, and hope they follow your wishes.