I performed a whois lookup on the domain, and it's from late 2023, the first red flag. That's why it's not indexed, and there's no mention of it anywhere. When I asked him where he got this exchange, he said a person from a crypto channel on Telegram contacted him—second red flag. This person has no references beyond the Telegram channel and is asking him to invest more money while urging him to keep the operations secret.
It's nice to know that you can at least sense some red flags. The fact that he got the buying/selling portal through some stranger on telegram means that it's 99% scam if I am being lenient. Advise him to stay away from the too-good-to-be-true deals and if he is still in doubt, invite him to read through the comments in this thread.
Also, why don't you do the community a favor by mentioning the so-called exchange here? Members will help to dissect and give out an alert if they see more red flags. This will help anyone else in the future who is trying to do their own research about the portal.