If you call something a duck and then put handcuffs on it, I'm still going to call it a duck even if you claim it isn't a duck anymore.
That's uh...certainly some kind of analogy there.
Consoles are really really just general purpose computers.
They're the exact opposite of that. They're highlyspecialized, that's what makes them consoles.
They're specifically engineered devices to work best at a subset of tasks that a PC can do. They're locked-down by the manufacturer. They're subsidized by the parent company (not always, but certainly recently) so that publishers must pay a fee to release software for it unless they're restricted to a narrow development environment. They are engineered to stress polygon and pixel shading performance over general computing (tried IE on the 360 lately? Christ an Atom netbook runs rings around it). If they were truly "general purpose", you would be using them as general purpose
Now, with the 720 and PS4, this may change somewhat - especially if the rumours turn out to be true and they're x86 based with lots of ram. That still doesn't change that they're going to be locked down and heavily engineered for games and media consumption over content creation...probably. If MS allows you to hook up a keyboard and mouse and anymore can write code for it, then you'll have an actual argument.
The fact that some hacker may eventually find a way around the protection is utterly irrelevant if the market is so niche that software developers can't cater for it (and especially since they can legally ban you from their gaming networks when they encounter a hacked console).
Software is what makes a platform "general purpose", not some theoretical possibility of what you could do with the hardware if given access for pete's sake.
Arguing that they're the same as PC's because you might find a console with the specific vulnerability in their DVD firmware that allows you to install arbitrary media players and pirate games and hope that it won't be bricked when you put it on the network is ridiculous.
The fact that I can hook up my PC to my TV and plug in a 360 pad does not make it a console, as the very attributes of a console that make them attractive to the general market - their accessibility, reliability, affordability and specific focus - are not present. It can act like a console, but it's not called one for those reasons. The same is true as the inverse - hooking up a monitor to my 360 doesn't make it a PC, as it shares little of the qualities which make a PC a PC.