No, definitely wouldn't presume they're friendly - and they'd run risk of 'friendly-fire' if they were actual allies.
And this is tip of the ice-berg of all the scripting Larian would have to do to incorporate goblins as a player race. Your goblin PC would be treated something like Sazza. Zevlor might even insist you not be allowed to enter the grove. Aradin, Erka and whoever else might simply decide to end you regardless of whatever Zevlor eventually says.
That's the deal with being a goblin. Otoh, you'd probably integrate much more easily into the goblin camp.
But end of day, we're just talking about less than half the content of Act1. Normally Baldur's Gate would be a problem but it's hinted at that things are going to be far from normal in the city.
