We don't know this,
we don't know why he got his account frozen
we don't know why he don't want to verify his identity
and as far as i know this is a common practice in all exchanges, just an example Binance do this all the time.
And it seems like small exchanges are being forced to implement KYC, Cryptobridge implement it, soon Stex and Crex will also implement, only Coinexchange still on the wild west side.
I was reading this article https://ambcrypto.com/shapeshift-is-being-forced-to-implement-kyc-aml-policies-says-erik-voorhees/ practically all exchanges are being forced to implement KYC

You must also watch https://www.youtube.com/watch?v=8DZGoDgRGNE