I don't know if it's YC's fault per se, but it sure doesn't reflect well on them when the first link on their giant cheerful "look at all our companies!" list is a dead domain serving malware.

YC owns 6% of the company when they go through their program. This stake is diluted further in future rounds of financing.

This is not enough stake in the preferred shares to dictate anything.

Sam's New Deal is for 7%, but I believe YC has re-up'd on some companies in the past.

YC following on is a very recent policy.

Before, their stated policy was never to follow on, in order to prevent signaling risk.

Has signalling risk gone away, or has YC expanded its appetite?

YC Continuity now participates in every following round, up to something like a $350m valuation. So they follow on for everyone, to eliminate signaling.