There aren't a lot of mass effect core accidents. At least not anymore. They say that you're more likely to be struck by lightning, that the core on your hoverbike is 99% safe.
Based on the explosion, Garrus figures this is the 1% of the time that you're not supposed to think about.
He picks himself up off the ground, checks the hoverbike. (Wrecked. Obviously.) Checks his guns. (Fine.) Checks his surroundings.
This... isn't Palaven.