John mcafee didn't know about zcoin, or may be xvg gave them decent stash for his editorial review/thought/tweet feel free to call it bribe, I wont mind, but mcafee might mind
I don't think he really want to say to the people that they should buy XVG.
He's generalizing the privacy coins but his main highlight is Monero, I have watched an interview of his and he told that monero is the one that is being used now in some deals all over the market who wants privacy.