This is a fine comment:
“I own a sofa. I can arrange the cushions on it in any pattern I like; if I couldn’t it would reduce my rights to my property. I also own a hard disk, and I can arrange the magnetic alignments on it in any pattern I like; if I couldn’t it would reduce my rights to my property. So to the extent that you believe in rights to real property, you cannot also believe in rights to imaginary property.”
The concept of IP-as-property (and hence, of copyright infringement as theft) is a ridiculous fiction: copyright is nothing more than a monopoly on the production of a particular product or service granted by the government to a particular individual or business, in theory because the government believes that the incentivising effect of granting the monopoly outweighs the loss of freedom and utility caused by granting the monopoly.
In other words, it’s as far from libertarianism as you can get: if you support IP laws [*], that shows that you think a) that there are areas where deliberate government planning produces better results than the free market; b) where this is the case, it’s right to reduce people’s freedom for the greater good; and c) the production of plans, inventions, blueprints and artworks is a situation where this is the case.
[*] As a believer in a mixed economy, I do support IP laws and have no intellectual difficulty with the argument above, although I’d prefer penalties for infringement to be smaller and solely civil, and for all copyrights and patents to expire 5-20 years after creation (depending on content type). Curiously though, many of the people who argue for tough IP laws generally argue against government interference in business.