It could be a working gun, but because they say it isn't, I would believe them.
As Rusty points out, it may be pot metal. Even if it isn't, if it was intended only as a decorator, things like the frizzen, the sear and the tumbler are probably not hardened like they need to be.
If they were left soft, the frizzen wouldn't spark and the sear and tumbler would wear out after a few hundred cycles making it totally unsafe to shoot.
The barrel could be a steel casting that would "look" just right but could have less strength than some aluminum alloys.
The springs would not have to have the power they need to function properly so they may be just enough to make the trigger, Cock and Frizzen move.
I'm not saying any of this is true because I don't have one of these guns but the possibility of them being true makes this a questionable bargain. :hmm: