It seems that the formula should be adjusted to account
for the conduction angle, e.g. Rl should be smaller by at
least a factor of 2 to compensate for the conduction
angle. What am I missing?

More current is flowing thru the transistor when conducting than would normally
be used if class-A ? ... this would average out because it's being pulsed rather
than continuous.

As it's a tuned circuit, the tuned circuit would carry on dishing out current
into the load thru the rest of the cycle - stored from the pulse of current when
the transistor conducts.

Clive