AFAIK Whirlpool helps to lose trace of the coins through obfuscating the transaction trail. It doesn't change the reported amount of Bitcoin bought from a regulated exchange, but it at least doesn't make it easy to find out what wallet those coins eventually ended up in.
Discussion
Im guessing if you send someone that bitcoin to someone else KYC would remain
They could trace the trail from the exchange if they wanted to without whirlpool, and you are on the hook for proving you still have that coin to IRA/CRA otherwise you will have to pay capital gains tax. In Canada that's 20% off the profit from buying price
The person receiving those coins you send p2p would be KYC-free from the receiver's perspective, but not yours.