NO, he won't toss it. He can't, but if by some supreme stupidity on his part he does then he will be overturned by the feds, simply and quickly.
He can't toss on grounds of state unconstitutionality since it is a state amendment, he can't toss it on fed unconstitutionality because the feds have ruled that it is constitutional for the states to ban, or allow, homo marriage. He has no grounds for tossing it. Period.
Time to wake up, pal. A lot of these judges have serious God complexes and quite frankly, an amendment to the California State Constitution should be immune to court challenges in the first place. And yet, look where we are.
Don't tell me what he will not do. Just pray he won't.