It is allowed, but certainly not recommended, unless you have no other option. This only then applies for DVD-Rom's that break/stop working, since you can just re-download the download version from the official site if you opted for that.
But that's not what this kid had in mind. It was already dealt with and he came barging in with more of the 'it's perfectly normal to google stuff and download it for free illegally' attitude that a lot of members of the younger generation seem to have. Which I dissapprove of.
And the rule I mention to that effect, is that you can't promote piracy, so to speak. Had it been well informed and substantiated and perhaps even backed with the quote of me saying that in case of emergency it's okay to use an illegal copy, I might have reacted differently. Hope that clears it up a bit.
It's a grey area, and it depends on how it's been suggested.
Fred