Lesson learned for them is that you can never rely on the http referrer because it can be removed/updated/spoofed etc. A team that runs Linux should at least be aware of that and not block a website based on this value.
The actual lesson learned here I think is that certain communities don't have respect for the social contract when it benefits them. Though I suppose you are right, a team of linux users should never have expected a site ran by a venture capitalist firm to respect the social contract.