The billionaire tax is on the ballot — but so are the weapons against it. Google founder Sergey Brin has launched — and largely funded — two ballot initiatives that take direct aim at the tax proposal. One of Brin’s countermeasures would ban taxes on personal property, including retroactive taxes. (The billionaire tax proposes seizing 5% of the wealth and assets of its targets). If it receives more votes than the billionaire tax, then under state law, it would prevail. The other countermeasure would require audits of new taxes, and would require the proceeds from the billionaire tax to be spent on education — not on health care. That would prevent the SEIU-United Healthcare Workers West, the powerful union that launched the billionaire tax, from benefiting from it.…