While your “fact” remains as fact, legal language has evolved to extend the word “theft” to the digital world — at least in the US; I couldn't find a reference for the word being used in other legislations.

“Content theft” is just a popular expression for “electronic theft” or “digital theft”, but I didn't find a reference to that expression in legislation, US or otherwise.

I hope that clarifies your doubts

The point is about 'theft'.

There is no theft in illicit copy, as I still keep my original data,
while 'theft' means I don't have them anymore. This is a fact, not an opinion of mine.

While your “fact” remains as fact, legal language has evolved to extend the word “theft” to the digital world — at least in the US; I couldn't find a reference for the word being used in other legislations.

“Content theft” is just a popular expression for “electronic theft” or “digital theft”, but I didn't find a reference to that expression in legislation, US or otherwise.

I hope that clarifies your doubts

The point is about 'theft'.

There is no theft in illicit copy, as I still keep my original data,
while 'theft' means I don't have them anymore. This is a fact, not an opinion of mine.

Tateru's examples of copying DVDs, photocopying books etc. don't rely on a criminal method to obtain a duplicate. To a degree, using a tool like GLinterceptor on your computer to duplicate textures and meshes is also not a “crime” (only your own computer is being hacked). Creating a software application that logs in to Linden Lab's grid and subverts their (few) protection mechanisms, deliberately violating ToS, and making a copy of content that way, is cybercrime.

But I agree that all this is arguable in court, and a good lawyer might be able to wriggle their client out of the “criminal” notion, possibly by arguing that Linden Lab does not enforce their ToS strongly enough and that they accept people who log in to their grid in violation of ToS and makes little to prevent that. A judge might be persuaded to believe that if the owner of a third party grid doesn't feel “intruded”, there cannot be an “intrusion”, and in that case, it would mean there is no crime.

Nevertheless, assuming that Linden Lab acts in good faith protecting their ToS, we'll have to assume that they are not happy about people using special applications to break into their permission systems and copy content. If that's a valid assumption, everyone publicly distributing a ToS-breaking version of the SL client (or a libopenmv-based tool) and everyone using that tool to copy content illegitimately, could be accused of computer intrusion (cybercrime), and the terms “content theft” (implying there is a criminal element on that action) would certainly make sense.