is this a red flag?

my wife and i are exploring adding a friends with benefits to our relationship. we only date together. we're both women.

we met a man on an app who says his wife is aware of what he is doing and she actually started the conversation about opening their marriage.

cool. fine with us.

we asked that she be part of a group chat (even as just a lurker) and he said she didn't want that because she was an introvert and that 'isn't her interest.'

we have only met in person once, just to talk and get to know each other. we have only be communicating for about two weeks.

what do you think?