Why does every article about this talks about the energy per transaction? Energy spent is completely independent from the number of transactions.
It's like making car efficiency relatable by saying that a car can go 180km/h using 5 airbags.
It means that to revert a 1 hour-old transaction, an attacker would have to consume double the energy the whole bitcoin network expended in that hour.
More energy expended == more security.
Number of TX is totally irrelevant.
Cap is irrelevant in this context.