There is no doubt that Walter is a nice guy and a registered Republican. Those items alone do not earn you an endorsement nor election. Walter is right on illegal immigration and some other issues. He is deathly wrong on other issues that strike at core Republican values such as private property rights and the rights of free enterprise (such as essentially banning the right of pet shops to sell pets).
To support Walter would have siphoned off Republican votes in the non-partisan race from more viable pro-business candidates such as Bob Hertzberg or even Bernard Parks - and deliver the third floor to Tony Villar.
Boi from Troy has a great blow by blow of the shenanigans along with interesting commments from disgruntled Republicans. LA Voice also has a few thoughts as well.