That is true to the best of my knowledge.
I am not a lawyer but I think that "actual malice" is based on foreknowledge that what is being said is a lie and/or a reckless disregard for the truth.
What Trump's lawyer is doing is warning these parties that what they might be saying in an ad is a lie...and that draws in the "foreknowledge of the truth" as well as the "reckless disregard for the truth" issues.
It's not so much a matter of who would win such a suit as it is a warning that such actions might lead to serious legal entanglement.
In warning all opponents to be alert to the use of lies in ads or otherwise, he is raising the "reckless disregard for the truth" issue and putting them on notice that he is willing to defend himself in court.
Very smart move considering the GOPe will try to play dirty. This will give them pause.
“foreknowledge of the truth”
Yes, the preemption then is VERY brilliant because Trump could then prove ‘Actual Malice’