Chaos Gym with modern Plus Power text

[cabd]

I assume my opponent cannot use the effect still, but I wanted to confirm.

The compendium has the ruling for the older text:

Q. Chaos Gym is in play. I play a Plus Power. I flip a tails. Can my opponent use it on their next turn? If not, why? Are there other cards that can't be used?
A. They cannot. Chaos Gym will not let your opponent use trainers that must be put into play. Sorry for confusing you [earlier], that was our mistake in not checking the card text first. (Oct 19, 2000 WotC Chat, Q67 & Q78 & Q81 & Q90)

But with the new errata, I just wanted to confirm this has not changed.

 

[PokePop]

Of course they can use it. It's not put in play any more, right.
Of course, it's only in effect during that turn, and it adds to damage done to both Actives.
But if they want to increase the damage to themselves, they can do it.