That screenshot is part of UnlimitedHealth's signature, it appears below every post they make. If you want one, you can add one to your profile at https://mccentral.org/community/account/signature. Regarding the original post, as Unlimited said TPA Trapping is allowed on factions and prison, and so is scamming. If someone ever sends you a random teleport request, I'd just ignore it or put all your stuff in a chest before accepting.
Tpa trapping is only allowed on factions and prisons, along with a few other things. Regarding if it’s legal then yes because it’s a minecraft server and abides by all the laws I believe in every single country. ;). But yes, it is allowed on prisons.