Darui could KO Deidara with Kuropansa/Laser Circus while he's making the C4 statue. Or fire a Kuropansa at the C4 statue itself, rendering the nanobombs useless.
Deidara shits... Guided missiles dodges his ration and blows him to pieces... Darui doesn't have 3tomoe cm2 nor snakes to protect him and Sasuke vast versatile ration abilities...
The trajectory and direction of Darui's Ranton beams can be manipulated; he could simply intercept the guided bombs before they hit him. Darui's also fast enough to dodge them if Deidara only sends out 2 or 3.
Deidara shits. Ranton, raiton, or whatever the **** has rai in front of it isn't going to stop a barrage of explosive clay birds or a giant dragon coming at you.