If taxes are theft, the virtue of theft is to be reevaluated.
Theft is considered pretty much universally vicious. The exception to theft being vicious could be argued to be stuff like stealing the bare necessities to live out of poverty, if you are barred from work without any subsidies and have children to feed. The vicious nature of theft is why certain political debators claim taxes is theft - it is a way to demonize taxes, and shorthand explain why taxes are wrong.
But here's the thing. Taxes have a lot of good consequences that people like.
So if you want to argue taxes as theft, you complicate the nature of theft, because theft is in that case no longer a (near) universally vicious action. Taxes have a massive lot of benefits, so if you want to say taxes is theft, you argue that theft can inherently have a massive lot of benefits. It complicates your anti-tax, anti-theft position instead of reinforcing it.