Nah, if the clients sent their coins to non custodial wallet and then send to CEX, there's no guarantee the CEX will not do the same. This called as conceal Bitcoin address and few CEX publicly stated in their terms if they're against that.

The safest way if you want to use CEX is, you have to ask your client to send the coins from CEX too, AFAIK some CEX allow to send coins via account's names.