They dance because they have 2 different upgrades, one that is AI and another that is AT. It means that want to prioritise one and then if they want to prioritise another they need to reposition. Same goes for captain (thompson and zooks) and any other infantry that has such a gimmicky weapon choice. Making them to choose between upgrades would most probably solve dancing problem.
They dance, because they have shitty cover seeking twitching that ALL squads used to have and relic decided to fix them all, every single one-except guards.
You're talking about situations where both vehicles and infantry are present.
Guards dance even if single squad is before them.