I think you’re asking why did he attack Omni-man one-on-one? If so, I had the same thought - it was suicidal. His best strategy would have been to attack from behind with gadgets that blind him and/or use some billion$ tech / armor to actually land a sizeable punch.

In any case, most of that fight was the guardians attacking him alone out of shock/anger rather than actually trying to work together and use their powers in a complementary manner.