I have no problem standing outside. But, I also noticed that Coach Troy often has you standing up in a very light gear. This REALLY hurts my knees, and isn't a situation that translates outdoors. I always use a harder gear with a lot of resistance when I'm standing up outdoors -- if I can spin an easier gear, I'll stay seated.
When Coach Troy instructs me to stand and the gear is so easy, I either shift up to a higher/harder gear and stand, or use that time to do a high-cadence interval.
For 3 days, I get to part of a thousand other journeys.