Just to draw a bigger spotlight to it, the restricted hours at the JFK Lounge only make it available between 5AM and 8AM, which is certainly pretty restrictive. Still, I tend to take early flights and its nicer to have options (Centurion, Delta, Virgin) at JFK.

Edit: OP's article doesn't talk about guest access but the Guest Policy on Virgin's page suggests that you can bring in a guest provided that they are also simultaneously entering the lounge with you and flying out of T4 on an international flight operated by Virgin/Delta/Air France/KLM on that day. However, Virgin's page has not been updated to reflect the fact that the Amex Platinum grants access as of yet.

Edit #2: Taking a look at the Global Lounge Collection page for the VA Clubhouse it looks like the Guest access is pretty plainly spelled out. "2 Guests and children under 2 are admitted free". For some reason I can't link directly to the Clubhouse page but you can find it pretty easily from the link I've provided.