I think it's a much smaller signaling risk, especially given how much time has passed and the number of founders (9 total, including Musk).

The Paypal Mafia tends to structure their companies this way... a large, tiered system of founders and junior founders. This is more like losing an early team member than, for example, a Collison.

(Also, it's ironic you cited OpenAI, since it did lose a founder... Musk)