Possible, but I highly doubt the differences are significant enough to make up the deficit. The other side has one or two more workers, which is just an insurmountable material advantage. If you back off to recharge your shields, I return to mining and get the resources for another worker or two (plus, my guys can recharge, regen, or repair too).
I'd argue that with AI level micro, the Protoss probe shield regen advantage would definitely come in play. Shields regen only when out of combat for 10 seconds and they regen at 2/second after that so it just takes 20 seconds to regen 20 shields.[1] This could definitely come into play enough, if micro'd enough, to make a difference, maybe... It'll be exciting to find out.
20 seconds is pretty long. Your opponent is up 2 workers on you, so assuming perfect micro from both sides, the defender can use one worker to continue to mine minerals and pump out more workers, while microing with the other 11 vs the attacker's 10 workers.
Workers can fade through units (unless they are sieged) when they collecting resources (minerals, vespene). So Idra commanded his drones to mine minerals and canceled the command shortly after.
This is common technique, mostly used to get scouting drone back through a walloff (own unit stands on "hold" in a small choke) or when a mineral line is under siege (e.g. Siege Tank, Liberator), the player can select all his workers to mine a single mineral patch (has to be spammed, otherwise workers redistribute) outside of the siege range until they siege is cleared up.
