If I see any resume with RSI on it, here's how I read it:
* I think less than 1% of the high school students in this country (the US) are aware of summer programs such as RSI. Knowing about RSI, let alone being selected into it, is a strong signal that in your pre-college years you were very invested in math and STEM.
* even if you don't have a very prestigious college degree is not a negative signal anymore from my point of view. At 17-18 we are all very fragile beings (and we keep being fragile until at least 25), so lots of things could explain why you didn't get into a top university. I would inquire about that, but I would expect to hear some reasonable explanation (and I wouldn't mind if you simply told me it's personal and you don't feel comfortable going into those details).
* I would ask you if you participated in any math or CS competitions in high school/ college.
From here, lots of ways to have a pleasant chat for about 30 minutes.
I am not from the USA (there is some number of international participants). So applying there is considerably more difficult than for a US person (and the effort goes in non-STEM things such as the application procedure).
When it comes to signals, I like your approach for looking at them as hints, rather than judgments.
