Two points:

First, even if you are able to borrow functional language from a contract without infringing someone's copyright, that doesn't make it a good idea. Heroku's terms were written for them and their specific business risks, governing law, etc. Your own PaaS business may have different requirements. And copying wholesale probably is infringement.

Second, by "IP free zone," I'm talking about people's attitudes and behavior towards the materials they borrow from--that certainly doesn't express a legal conclusion about it or mean what they are doing is not infringement.

I've had a similar question about the validity of free software licenses that only permit verbatim redistribution, and whether it's possible to use ideas from such a license in another license. The idea of a license being under a license just seems alien to me.

If you look at website Terms of Service etc., you'll see that there's huge amounts of copying between firms which compete with each other.