If there is a problem that could be caused by people using the ability to switch, then HT should identify what it is and punish "them" instead of the ones that do not cause any problems.
Just devil's advocating here a bit, suppose you're on one country and see a carrier group horde from your side rolling a barely defended base. You switch to the defending side because it looks like a fun fight to have from that side. Reasonable? It's one reason I'd switch.
What if just before you switched, you happened to see a knot of C47s flying by the CV on their way to the base, headed toward the base being attacked from the south? Are you justified in upping from that base and heading south to intercept them? Are you morally obligated NOT to head south because of your prior knowledge of what is coming? Should you engage in that fight at all knowing what you know?
How on earth do you enforce rulings on whether people used knowledge from their previous country, compared to fortuitous circumstances?
Here's an example: Last night I was headed to a base to defend it from a horde that had been at it for a while. I figured I would go goon hunting, half expecting to be too late, but figured 'why not?' On my way there, I got engaged with another P47 and wound up having a duel with him which I won by a slim margin. Down 3 guns, I actually started to turn back and realized I still had enough control surfaces to take out a goon if need be.
I made it to the town, and through miraculous fluke got there just in time to intersect the goon's flight path just as he began to drop. Due to my awesome gunnery skills, he survived my first pass just as he was dropping, and I turned back and managed to shoot down a few troops in their chutes and kill the goon.
With that situation, what if I had just switched over from that side and run that sortie? How would someone watching that from the server be able to distinguish that from a guy who had seen the goon take off from the tower and was headed there to intercept it?
Wiley.