Unfortunately, in the middle of a commitment of perforrming an action (i.e Suplexing the construct). I believe Pierce would not have time to lift up an object that size to completely shield you from that explosion.

My second point is that the change in the Golem's substance was ignored, ,eamomg Pierce had no knowledge of what was about to  occur. But, in the fraction of  less than a moment, a barrier was lifted to counteract that explosion. Even if this was the case, you would have to have a pretty big chunk of rock to do so.

Could I have an explanation as to how this would be possible?

Also, to quote the character profile for Pierce, his muscles are capable of "weak ki-blasts and even low calibur (7.62mm/.303 and lower) bullets even if his human skin could not."

Meaning Pierce still has the capacity to feel pain, and the pain from such an explosio of that magnitude  would be enough, (if not more than enough) to kill him.