That’s true until you factor in relativity, which the person above you was trying to avoid. Basically, if someone were traveling near the speed of light (and in the right direction) they would see the person get the text on the moon before the person on the earth sent the message. And it’s not just a matter of perspective either, if they had an FTL phone they could see the message received on the moon and then text the person on earth before he sent the message, preventing him from sending it in the first place.

The explanation for this is complicated, however, so I would suggest you look at the links provided earlier in these comments for a more comprehensive explanation.

So the main thing and again I'm not really equipped to explain the relativity behind this but I do think I understand it somewhat.

The main thing in the situation you're describing is that it's one way. Make it two way, imagine getting a message saying "don't send that message" from someone who has already seen the message you're about to send.

You can imagine this and that's part of the problem understanding the issue I think. But if this combination of events was possible very many things that we know to be true about spacetime would have to not be true.

If I got into a FTL spaceship, I could go out in space, turn around, come back, and interact with my previous self. I could even tell my past-self that I didn't find anything of value -- and that there's no reason to go at all. Maybe the original me decides not to go, and now there's two copies of myself on Earth.

These are the sort of contradictions that break our understand of causality once you introduce FTL.

You got your sentence wrong. You receive the message BEFORE you see the person through the telescope typing the message, i.e. it takes 2.5 seconds for light to reach us from the moon, you would get the message 2.5 seconds before you see the person typing it assuming the FTL messaging system was instantaneous.