As torry said you can create a scam accusation about them.
Why not just expose that modus on their telegram channel? Imagine if they will continue this type of scam it's possible that they can fool few from that 164k members.
You can also create a thread on reddit since it's also a place where people are lurking about ICO's.
Are you sure that it's the real devs of dentacoin?
I, nor the other members, can't post a message in their telegram channel since from the start.
It seems the comment/reply section is disabled to members. They (dentacoin) are the only one posting infos.
https://t.me/dentacoin_airdrop is the link of the telegram.
and they have a bot, too which is the one asking for the private key @DentacoinAirdropBot
Yes, it is very possible that they can fool a few especially that their bot is regularly reminding us to verify our account.