[magicalist]

non-competes are void in California.

[pessimizer]

Not based necessarily on a non-compete, but based on similar and concurrent projects, "trade secrets" and "proprietary architectures."

[x0x0]

only up to a certain seniority level

[tptacek]

[citation needed]

There are things execs do that line employees don't that can presumably make a CA noncompete binding, like, for instance, accepting significant consideration specifically in return for a noncompete. But I don't believe seniority is itself a factor that can make a noncompete binding.