nothing has yet surfaced giving veracity to this curious claim
Yes. And it seems in another thread, a credible source--a gov official--makes the case that the President's executive powers to conduct foreign policy (which are independent of the other branches of the Federal government) give him free rein to reveal even classified information with foreign officials if he believes it will benefit the US.
That argument makes sense to me, since the USC does make the three Federal branches co-equal, and gives the President executive powers.
>> give him free rein
of course, especially of the recipients of said disclosures were deemed by POTUS to be vital operatives.