First of all, you definitely would. Standard practice is 1) report the bug privately, 2) wait for a fix, 3) get the go-ahead to publish your report and take credit publicly. That's how it always works; that's how security researchers build their reputations and careers. I guess you just weren't aware of that.
Second of all, even if you wouldn't get to publish it, that is horribly selfish reasoning. Putting millions of people at risk of having their information stolen for the sake of a popular blog post?
In this case, Google put millions of people at risk, and dejanseo actually contributed saving them.
But while there are a lot of domain where I don't accept the reasoning "someone else must have thought about this before", finding vulnerabilities is somewhere where I can't help but believe that every publicly disclosed vuln has probably been secretly exploited and sold for years.
(The only data point I have behind that is that there are nations level agencies pretty much dedicated to finding those, and they've gotten really good at this (cf Stuxnet !)).
So, while by conviction only, I highly doubt any independent white/gray hat vuln finder will ever be the first to find it, and I applaud any kind of disclosure.