I can buy that he could survive but it needed to be justified
Pell is supposed to be the strongest fighter in Alabasta so I can buy that he could tank or escape the blast wave of a nuke. What matters for a sacrifice are the intentions after all. But that bomb and how it could wipe out all the citizens of Alabasta is a key point of the finale. Without explaining how he survived, we just have to make assumptions. Which honestly does make things fairly confusing