It's pretty necessary. It's not necessarily meant to amend prop 19, it's meant as a mechanism to implement and better define prop 19.
Here's an example of what I mean;
That is impossible to enforce because it lists no specific penalty. A senate bill to clarify is absolutely necessary.
There is no one better to write this than Ammiano. The assembly does have better things to do than deal with this, which is why they'll pass this and get it over with. They need to pass something to implement prop 19, they have other things they want to do. That's exactly why this will get through. They aren't going to want to waist time fighting over this.
Ammiano doesn't need to pull stunts to get votes. He's possibly the most popular politician in the city. He got 83% of the vote in his last election. He has his assembly seat locked up. He represents the Castro, Filmore, tenderloin, HP, and the haight. Unless a half black/half latino-transvestite-pot smoking-socialist-jazz musician is running against him, he's in pretty good shape.
I think voting against Cooley is WAY more important than prop 19.