If Uber had made shares available to unaccredited investors, they would have gotten in trouble. I'm quite certain that the grandparent was not in the list of Travis's top 35 people to raise $10k from, and as such he had no legal opportunity to buy shares, even if Uber had wanted to sell them.
Makes sense why you feel this way.
What I will say, is no one stopped you from investing in Uber, besides Uber. Tomorrow I can go out and sell half my C-Corp to a friend. Legally, no one is stopping me, besides me and my contract(s). My company isn't publically traded, and as such, I haven't released shares to be bought and sold.
That being said, if you're talking about "accredition" - that shouldn't stop you from being able to invest in a friend's or aquantences company. At least until you have 35 of said people..
Which I agree is B.S., at the same time - it's just a way to ensure you don't get massive companies like Uber getting billions of funding and providing no services. It's an attempt at curbing a dot-com-esqu bubble. Overall, I do think this is government over reach, but I do see the point.
There are ways around that FYI, for example there isn't a reason a financial advisor couldn't invest on your behalf.