Zenefits wasn't a competitor to ADP, but it seems that ADP thinks that they may want to roll out a product that competes with Zenefits, so now they are trying to clear the playing field before they step onto it.
This would be similar to Apple deciding to screw up some 3rd party apps that run on OSX because they are working on a product that competes (but has not been announced or released yet). (And then you coming along claiming that said 3rd party software was a 'competitor' to Apple, so should just 'suck it up').
Zenefits wasn't a competitor to ADP, but it seems that ADP thinks that they may want to roll out a product that competes with Zenefits, so now they are trying to clear the playing field before they step onto it.
This would be similar to Apple deciding to screw up some 3rd party apps that run on OSX because they are working on a product that competes (but has not been announced or released yet). (And then you coming along claiming that said 3rd party software was a 'competitor' to Apple, so should just 'suck it up').