Too good to be true.
He is willing to send BTC first, but he sends with RBF and a very low transaction fee, then he asks you to send USDT and insists a lot, since I've said him to just wait for 1 confirmation and I would send the USDT... chat was over and he used RBF to get back the transaction.
It does not seem that what he is trying to do is smart, but rather an attempt to deceive the beginners. Can you attach proof of screenshot or the transaction link or any details so that we can verify your words.
In general, until you confirm this, it is better to consider @aaroncryptt is a
scammer.