I honestly don't know when the symbol shows up as I tend to make sure there is enough spots in cover before ordering squad to move into it, so when they arrive and the symbol shows up they are all in cover. But it is true that squad with one soldier not in cover will still have the symbol, and that could be something to be changed.
I still don't think that allowing some part of squad to be out of cover unsuppressed is a good idea. This could make some directional cover positions really hard to suppress with flanking fire and some squads, like shocks, PPSh cons, volks, BAR riflemen and so on, can kill whole machinegun team with 2 or sometimes even one member that runs past mg without being suppressed. Not to mention that squads with nades have one special member that always throws nades, if that was the one someone extracts from the squad, all mgs would be doomed by exploiting such mechanic.
yeah you are right, and as I said it's not a big deal, so I think it's the best if it stays like it is