You probably want these icons at 50% opacity to match existing styling of the block.
Also, as others have noted, it makes the page look overly busy with secondary items, so they are probably best kept hidden by default, shown on hover and fronted by a single (smaller) icon, like a checkmark. That is, you hover over the checkmark - you see it expand into the list of icons.
I'd still love if those icons/links were actually hidden in a popup and not removed altogether - they serve a nice discovery purpose for peoples' Github / FB / Twitter accounts and personal websites (inb4 privacy - this is already public info for HN users if you put a keybase proof in your profile, just usually requires extra two clicks to get to).
EDIT: just installed on mobile. Works great, but the clutter introduced by the icons is extra pronounced on the phone.
A popup will happen eventually, but that'll take a bit more development effort.
The as-a-dropdown-from-Keybase is probably the best solution.