Fascinating.
Actually, I hadn't thought of that, but I think that the idea put forward by both
@lizkat &
@Thomas Veil - feeding the loathsome Mr Trump harmless, or peculiar - or, at the very least, easily traceable - stuff to see whether it surfaces somewhere where it shouldn't, to be an excellent idea.
However, while it is clear that Mr Trump cannot be trusted with national security briefings, and that Mr Biden is right to consider revoking Mr Trump's right of access to same, this is something I would prefer not to become a precedent, for, it could become yet another nasty little tool to be deployed as petty revenge in a post transition environment.
I think that while Mr Trump's right of access to such briefings should be revoked, and Mr Biden is perfectly right to do so, it should also be made clear that this is not considered a precedent, but, rather an aberration, on account of the peculiar nature of Mr Trump's tenure.
This is because - for a currrent President - former presidents can quite often serve as a very useful (and, irrespective of political complexion loyal, and supportive) source of advice and counsel and experience and knowledge to a current administration.