The surface video is not relevant. One doesn't fly on the surface. You could have conditions like that, with tops at 5,000ft. As regards tops at 20,000ft the data does not support that except in patches.
He may have had an FAA IR but as it was a UK reg a/c he would not have been allowed to plan to exercise its privileges.
One can check the name on the FAA pilot database - a very useful thing this is too; try it sometime for people you know
He had an FAA piggyback PPL (2006) but no IR.
He could have used an FAA IR in a G-reg for IFR (worldwide) but only outside controlled airspace (ref ANO article 26).
For a VFR-only pilot, I agree this would have been a total no-go flight.