Just pirate TurboTax. Torrent it, set up a fresh windows VM with Internet access via VPN, install/update turbotax, crack it to get the state version, make sure it's got live versions of all the forms you need, disconnect Internet access (never to be reconnected), copy previous year's data files to VM, do taxes, print out and file by mail, copy data files off to long term storage, save VM image in case you need to revisit any time soon.

Sure, it's a bit tedious. But short of a privacy-preserving libre solution or just doing them manually with fillable PDFs, you'd have to do most of that isolation prepwork anyway. So fuck 'em.

P.S. The directions for modifying .NET assemblies to crack TurboTax are simple and easily followed by anyone with basic programming skill. So if you're fine trusting Intuit you could obtain the installation files from them directly, crack it yourself, and even have e-filing capability from what I understand.