All exchanges that froze your finds are a red flag and I'd avoid them. If you can and want to trade I'd suggest going through a reputable exchange that does KYC. If you want to stay completely anonymous then I'd suggest try to find Bitcoin ATMs either in your country or another that supports them, and send the Bitcoin to the exchange, trade it for your cryptocurrency of your choice, and then back to your wallet.
Most exchanges that are kyc can seize your funds, even if you do kyc with them, they are going to freeze your accounts and your kyc is what they are going to use to further do an investigation if they are suspicious of your deposit. I don't know what you are telling him to go and use centralized exchanges when they are the causes of why funds are AML compliance, they can seize your funds if they see anything that is suspicious unless you are buying fiat from your bank transactions.
Some instant exchanges don't ask for kyc but they can ask you for information to clear yourself before you can be able to access that money. The ATM you also suggested have terrible fees, except if in his country theynhave good services. My best advice is decentralized p2p, they have good buyers, even though the fee rate to local currency might be higher, but you have nothing to worry about coin freeze by anyone.