To make sure we're talking about the same thing; the pink line in the second graph on the techcrunch article is what you're talking about when "the bubble goes parabolic".
That pink line represents the number of seed deals completed, not the amount of money in the system.
Unfortunately, I cannot download the original dataset that Mattermark is using, but using a dataset from Pricewaterhouse Coopers[1], and data from FRED[2], I have run some statistical analysis using R.
My results are here: http://imgur.com/a/eFzs1
In short, the only statistical correlation I can find between QE and Seed capital is a negative one, which would contradict your original hypothesis.
[0]https://medium.com/mattermark-daily/why-is-the-number-of-see...
[1]http://www.pwcmoneytree.com/HistoricTrends/CustomQueryHistor...