They created urgency. A case otherwise could've taken years for a first decision and would've been purely theoretical. They now need a decision within 14 days and can prove significant damage if the courts rule in Apple's favor (whereas Apple's damage is negligible if they're forced to leave Epic alone for a bit). The court case will be long either way but Epic can now show how harshly Apple reacts to enforcing the 30%, something they couldn't have done before.