Where did I say that? I'm saying one of the purposes of BTC is privacy from government intrusion. If you pay a tax liability in BTC, they're going to know you use BTC, and thus will be more than likely, if given at some point it is heavily regulated or made illegal to use, will know who to target for investigation.
Just because you pay YOUR taxes with btc, doesn't mean you sent it, you owned the btc, or that you will continue to use a service that pays your bills with btc.
BTC is a currency, a means of exchange. If you go into a money center that has btc service, instead of sending money gram, or wires, you could send BTC faster and cheaper so that's how you opt to pay your bill. You give the cashier $1200 they send $1200 worth of btc to the IRS on your behalf.
Don't be so paranoid. You give them too much credit.