I don't think anybody assumed you're out to trick people, however "open source" has a very clear definition [1] which implies that the work in question must be accompanied with a license respecting that definition, in order to modify the work and further distribute it. We as software developers have learned to search for and take note of permissive licenses and are very cautious of fake open source, like for example Microsoft's infamous "shared source" initiative.

My disappointment is when people are diluting this term, because it doesn't mean just free as in beer and it doesn't mean just having access to the source code. It's much more than that and the definition couldn't be clearer. Many companies have tried capitalizing on this term without delivering and this has left a sour taste amongst many of us. And YCombinator amongst all organizations should be aware of this, let alone the lawyer that drafted this document.

But anyway, thanks for sharing.

[1] http://opensource.org/osd