Well, it's probably the best strategic move for them in the system.
I personally don't like the "top two get on the ballot" process in a system based mostly on parties. It'd be fine if we didn't have parties... but we do.
I much prefer IRV as an alternative.
True enough, though them doing this means that there is no real need for the Democrats to do the same. Only one serious Republican assures a Democrat making it to the second round in all races.
Personally, I wouldn't mind the top-two system if it included a NOTA option. I like being able to register my dissatisfaction with the powers that be.