> Is the removal of any content for any reason "censorship"? I don't think that fits conventional usage of the term

I think censorship is generally already considered to be any suppression of speech/communication/information. There are forms of censorship that many consider to be fine/justified, like taking down libel or removing inappropriate language in songs played on the radio, but it'd still conventionally be considered "censored".

The threat of 10 years in prison under the DMCA for providing information that lets people jailbreak/repair/reverse-engineer their own devices definitely fits the bill of censorship to me.

> If I steal an object, and the government takes that object away from me, would you call that government action "theft"?

If you see some state/company secret that you weren't supposed to, and the government prevents you communicating about it, I'd say that's a form of censorship. I don't think it can be analogized to stealing an object in a meaningful way.