A big problem with this is from my own experiences, despite the rate limiting on the API, it has far more access to historical data (eg, past tweets) than the browser.
Generally I think this is unlikely to happen because people who are freelancing often are doing so because their need is liquidity (read: cash, relatively soon) and not equity in a maybe successful venture. Thus they're looking to be paid now for work, not be involved in a longer term personal investment, whether in someone else's company or their own. So by definition, someone freelancing has very different goals than someone with the security and desire to be thinking about startups. For your question, I think you'd need to find someone who very specifically is freelancing but also is looking for a good startup idea, which I think is rare.
like was said in the article, a js in-browser implementation, if possible, would be great. Imagine being able to get back to your work from any computer of any kind, anywhere, without having to download any ides or set up remote debuggers or anything. a great idea that would be even better (and I think manageable) in the cloud
Possible that you're the first. I was going to do Piet but then saw your post, so I settled for Befunge instead to keep some two-dimensionality in there.