Actually, this plan could slightly reduce Democrat hegemony.
Jefferson would elect 2 Republicans routinely.
North California would elect 2 Dems routinely.
Silicon Valley: 2 Dems.
Central California: 2 Republicans.
West California: obviously 2 Dems.
South California: 2 Republicans ... but not as reliably.
That’s 6 Senators for each party — parity.
Not saying I’m in favor of this never-gonna-pass-anyway plan, but it probably would NOT further pad Democratic representation in the US Senate, and IMO would reduce it slightly.
More importantly it would divide the electoral college votes ...