This is good for Bitcoin.

This is good for Bitcoin.

What does unspent capacity mean? I fail to understand the message.
Samourai Whirlpool has mixed 6700 BTC which has improved the forward privacy of the users?
It means there are 6700 BTC worth of identical looking UTXOs out there (split across the 4 pool sizes).
When unspent capacity goes up, so does the size of the crowd that every single Whirlpool user 'hides' in.