Sure, when they say WhatsApp can’t access the encrypted messages they could mean that Meta/another internal group has access to the encrypted messages and they decrypt them in order to provide them to WhatsApp/whoever.
(Obviously, as someone pointed out, this is all assuming that he’s telling the truth in some legalistic way and not just flat out lying.)
Nitpicking; even if they have the keys, the messages can be encrypted. It’s just worthless as they can now decrypt them.
Sure, when they say WhatsApp can’t access the encrypted messages they could mean that Meta/another internal group has access to the encrypted messages and they decrypt them in order to provide them to WhatsApp/whoever.
(Obviously, as someone pointed out, this is all assuming that he’s telling the truth in some legalistic way and not just flat out lying.)