...there's a good chance he gets murdered by his own troops, as do some other argentine officers, meanwhile other argentines may take revenge on the civilians. it won't be pretty, but i don't think you are going to see a mini-stalingrad either, since alnost all the argentine forces were incapable of anything but completely static defence from prepared positions (which incidentally were usually poorly prepared despite all the time they had).
One telling fact here - after surrender the Argentinian officers were reportedly by and large very unhappy to be deprived of their sidearms. Not from any concept of honour, but because they were scared of their own troops and though they would need them for self-defence.
OTOH, Menendez might expel the civilian population and send them west in a futile attempt to bother the incoming paras' logistics, so we just get more military casualties but little civilians ones.
That might actually impose quite a significant delay on things - the rate of advance was very much controlled by the rate at which men and supplies could be moved forward.
Having said that, a few days of delay is all that it could achieve, at the cost of some pretty horrific international press: by this stage the British control the whole of East Falkland except for Stanley, including all of the high ground around Stanley.
They've got 105mm artillery forward, and indeed right before the surrender were engaging Argentine forces on the outskirts of Stanley with it. It should be noted that Stanley isn't Stalingrad here - the buildings are made of wood and tin, so offer essentially no cover against artillery. The civilian population have some value as human shields - without them the place is just one big target.
The Marines and Paras had spent the best part of ten years learning street fighting on the Falls, the Bogside and the Creggan while the Argentinians were scared, miserable conscripts who just wanted to go home.
Umm... you don't do FIBUA in an environment where you're fighting trained soldiers in the same way that you would patrol in Northern Ireland. You're not going to blow a series of Mouseholes to patrol down the Falls Road, for instance, or send a grenade through the hole before you follow through.
The British have indeed been training for it for years (ever since the Canadian experience at Ortona), but the modern facility at Copehill Down was only built in 1988. They'll probably be a bit better placed than the Argentinians, but the training that helps then will be for Germany rather than Belfast.