Nope not only do businesses have every right to be secular but most Americans don't know who Cesar Chavez is and should. Not to mention that Easter is a co-opted holiday stolen from pagans so really we should have Ishtar or Gaia up there if anyone.
It's an interesting choice that annoys me for religious reasons. It does not surprise me though. Had Google selected Jesus or something Christian, it would have been criticized, so this was really not a situation where Google could win.
It's interesting that so many call it the "religious right." There are plenty of democrats who are religious too, and many of them were not thrilled with Google. This may just have more to do with religion than politics.
I don't get why people are so upset about it. I've come to the conclusion that some feel that everything has to be about religion and the US. So, would they prefer the pagan (rural, country-like) representation of a fertile goddess symbolized as a cute bunny rabbit?
Google has only done one Easter doodle, back in 2000.