My bet is on it being plugged in, or he was particularly lucky to have bridged the cap across his heart with both hands. Probably the former, as the amount of stored energy isn't what would cause the burns described.
Actually picture tubes are highly overrated when it comes to danger from them remaining charged.
The EHT voltage is quite high,& they do retain charge for quite a while,but their capacitance is too low to supply a lethal shock.
The danger of those is not from the shock itself, but from the surprise making you do something else, like drop the set or smash your hand against the neck. I've gotten static shocks on dry days, those can be tens of kV and the secondary effects are what really makes you do something stupid, not the shock itself.
Back in the very early days of picture tubes,they were quite dangerous if dropped,but almost anything from the early 1960s on is very unlikely to implode catastrophically.
If you smash your hand against the neck,you may break that part of the tube & give yourself a dangerous cut,but it won't implode.
Back when I used to fix TV Picture Monitors & TVs,if we junked a CRT,we were supposed to knock the end off the neck to render them "safe".
We were also supposed to stand back & do this when the dumped tube was already in the dumpster.
It was incredibly hard to do,even with direct hits on the neck with lengths of galvanised pipe or star pickets.
No implosion if you did,just a gentle sigh.
On one occasion ,we had some tubes from very old 1950's 12" monitors--they
did go bang when we chucked them in the dumpster.