They don't actually have a lot of options. There definitely isn't time now to do the 'send it off to the sun' plan. It already appears the magcon shields aren't as effective as they'd hoped so there's no moving it to anywhere else secure (and again with the not really having time). Any sort of explosion or fire here would likely just serve to help spread it in ways they couldn't predict.

Smothering it is.

Gritting his teeth, Anakin reaches out with one hand (and the Force) to squeeze out the life they'd sensed before it could gain a foothold.