With the reference to carb heat he was then also not flying a Raven 2 (fuel injected) so even less room for error.
Simple tools like ibal and Gyronimo make flight planning easy, there's no excuse really.
Being hot and high around these parts, power management is an essential part of training.
Confined operations are all a standard part of training and checks.
If you aren't going to be taught (and practice) them you may as well go fly a stuck wing instead.