Why not just use a non-optimal domain name and buy the boutique domain when the startup in question is in a stronger bargaining position and/or has more cash? Lots of YC companies have done this and it didn't seem to be a problem. Even Twitter did it.
Bad strategy. Would increase the price tremendously. This is what I do and I operate on both sides of that business. This particular company got a million dollars for a domain in a similar situation.
