Deidara should actually have a slight speed advantage. If Laxus doesn't kill him before C4 then he's going to have a bad time.
C4 gets deactivated by a simple lightening blast. Why Sasuke didn't just do that was baffling because his chidori needles were deactivating his bombs in the beginning of the fight
he admitted he was testing the deactivation theory when he saw it didn't explode next to Tobi, but he wanted to make sure it wasn't just that Deidara didn't want to commit friendly fire.
Also a mere chidori needle wouldn't deactivate C4. You need a powerful lightning attack. For example Laxus' roar would suffice to break most of it up but of course him being naturally lightning also negates C4.
This is just a classic anti-character matchup. Laxus is literally anti-Deidara any shape or form.