What is property?

The links are there because, as I said, this is of course not the first time this ridiculous notion has been raised.

Inalienability of the self

Punishing non-violent actions with violence

Fraud in Libertarianism

Deterrence in Libertarianism

Alternative to intellectual property

What would Rothbard say about non-compete language in an employee contract?

Every single one of those links directs to a specific post, each offering the answer to your question. You seem to have a real problem doing any sort of outside investigation of your own.