I’m not informed enough to have an opinion on prop 40, but it’s disingenuous to say that she would have to sell $250m of her stake in in-and-out. She could take out a loan against her stake and pay the tax with the proceeds, then pay off the loan over time with the income from her ownership of in-and-out.
But she would have to do that (borrowing $250m) every year, and the company's cash flow might not be able to sustain the repayment in 12 months; and it the borrowing keeps stacking, then she would have to sell part of the company; and that's the point of the article.
I'm not sharing my opinion on the matter or anything, just correcting you that the California wealth tax is a one-time event, so the owner would only need a single $250M loan, not a new one each year.