A cursory google turned up articles saying that, with some exceptions, post-employment noncompete agreements are typically not enforceable in CA. My wild guess (with no experience in this area) is that the language claiming rights to future creations is merely an attempt to get around CA law on noncompetes.
The assertion of rights to the employee’s 24/7 creations during employment sounds like a no-moonlighting provision.
It is unfortunate that this was presented as take-it-or-leave-it and I’d have been very tempted to push back on that, to provide suggested edits to the future creations provisions that would be agreeable to the employee (i.e. cross them out), give it to HR and see. (My sibling, an executive in a large CA tech company, has edited his employment agreements before signing, though perhaps this is more expected in high-level positions.) Maybe this company is too small to have HR personnel and can’t afford the legal expense of negotiating employment contract provisions. Considering the awkward situation with the boss, it was probably best to walk away.