Does accounts get inactive/expired/liquidated if not used for a long time?
If so, what happens to the items and TCs of that account?

Acounts never expire. Theres still acounts from 2006 and 2007 that are never used but they are still there.

...mine also for example...

There were most likely used because when Toribash first came out you had to purchase your account for 10$.

Also accounts never expire and they will remain with the same name until someone decides they want that name and they send 100k to admin. The name will then be changed to (Originalname)_Depricated.
Also the items as well as tc will remain on the account until taken off by the owner of the account.