Although Zhou Tian's strength was sufficient that facing a direct hit from those crystal bombs would not lead to his death, the explosive power of the crystal bombs meant he would not feel well if hit directly. Therefore, if he could avoid those crystal bombs, Zhou Tian would likely prefer not to be hit.
However...
Just like the reason Zhou Tian's moves affected those True Gods earlier, though Zhou Tian anticipated that the True Gods would prepare for his attacks, he couldn't predict their current display. Thus, Zhou Tian had absolutely no preparation when those crystal bombs were countered back by the True Gods.
Therefore, with Zhou Tian completely unprepared, when those crystal bombs were rebuffed, Zhou Tian still had to face the threat from those crystal bombs.
