I call it "sign-up driven development", or "sign up to find out what you are signing up for".
Here's how it works - Create an account, import your YC application or enter information about your startup manually, then send the shareable link for your startup profile to investors by Twitter or Email.
I think many in your target group may be registration-aversed, even if well intended.
[LAST EDIT]: Now that I've looked more closely, in this case it's not obvious how to "grant access without registration", as you need HN creds to grab the application. Plus there's the inevitable issue of "investors" being spammed and unregistering. So, in your specific case, this onboarding flow seems reasonable.