If we didn't have a Van Allen belt, some bright scientist would say no life could survive on earth, because of the radiation.
Life as we know it evolved to deal with earth. It evolved to live with at atmosphere, with a van allen belt protecting it, with limited meteors strikes (because Jupiter protected us), with our sun, with tides, etc. etc. etc. etc.
Just because we can't deal with a series of Gamma Ray burst does not mean living creatures living under an ice ocean, feeding on volcanic energy can't survive it.
Basically, what's going on here is some one asked a Physicist a question about biology. You get an answer that makes about as much sense as if you ask Stephen Hawking if the tumor in your kidney is benign or malignant.