Am I going too far with that claim? Nope. I've argued it many times and haven't seen any response that's even remotely plausible. Here goes:
Most libertarians have no problem seeing why property rights in radio waves (i.e. the exclusive right to emit at a certain frequency) are justified.
Next, notice that IP (intellectual property) rights have the exact same form. Just as spectrum rights allow exactly one entity to form his property into a specific pattern (such that it emits at a specific frequency), IP lets exactly one entity form his property into a specific pattern. They are rights to configurations of objects rather than objects as such.
It is true (as many, many will remind me) that to broadcast at the same frequency as someone else "interferes" (!) with their "signal" (!). However, your judgment that there is "interference" is itself an arbitrary value judgment about the merit of someone's intended use. In exactly the same way, copying someone's ideas can interfere with their intended use.
Remember, the ether does not somehow "want" to carry information. It is simply one positive attribute humans have been able to wring out of it; if people merely loved to blast radio waves for the heck of it, the conflict wouldn't arise. So the characterization as "interference" is solely a function of the uses people want to make of it.
Unless and until you can make a libertarian case why one desired use justifies exclusion rights for specific patterns and the other does not, the cases are perfectly parallel.
There, that's all there is to it. Don't let the length of this post confuse you; the entire case is self-contained between the asterisk lines. I want to now briefly review my history of making it.
If you look at this comment and the preceding, you see Stephan Kinsella make a seemingly innocuous but actually damning admission: that attempts to differentiate the cases of IP and radio waves reduce to (the very arbitrary decision of) what counts a "relevant use" for purposes of discerning property rights boundaries, a distinction mentioned nowhere in Kinsella's widely quoted case against IP.
The argument persuaded some participants to reluctantly bite the bullet and admit that they couldn't therefore support radio wave rights either. (Yikes!)
You're rightly skeptical to wonder why I'm not quoting a peer-reviewed, published exposition of this argument, and indeed many have suggested I flesh it out and submit it to a (very ungrateful) libertarian journal. While probably a worthwhile pursuit, if I have spare time, it kind of misses the point of journals: to get results, whether they be new, useful scientific laws, or evidence in favor of propositions, or establishment that something is or is not possible. If the above remark by Stephan Kinsella is the best response he, the eminent opponent of IP, can marshal, we already have a result. Wanting it in a journal article is putting the cart before the horse.
I've probed other intellectuals on this and found similar inability to refute -- I'm just posting the best response I've gotten.
Comments are greatly, greatly welcome. Unlike some other people who shall remain nameless, I want to see where I'm wrong.
 A name is a label intended to refer to a proper noun. An example of a name might be Stephan Kinsella or Bob Murphy.