No. Trainer time is about allowing you to do more in the real world. If you can't transfer that, it doesn't help. You'd be better off using that time as you say. There's actually more going on here than it might seem. When I come back from a hard group ride, my arms and shoulders are tired. Why? Because I've been prying on the bars while i put out twice my FTP while seated, and I have what passes for a smooth pedal stroke. You can't do that with one arm. You won't be able to follow up a steep hill at those power levels. You are a little lighter without that arm and the upper body muscle that goes with it. Your strength will be long climbs. Train for those, ride them.

Be that as it may, it is said that in winter you train your weaknesses, in spring train your strengths. I'd work on putting out high seated power on the trainer, VO2max work, max effort work. Better yet, switch out the trainer for resistance rollers and make your training more like your experience on the road will be. I think that would be even more important to you than to the 2-armed riders.