To call it sinful is a bit much.
There can be disagreement on the timetables due to how a person wants to interpret scripture. I myself see Gen as a 24 hour day or something like that. I dont think it reasonable to stretch the meaning of Peter all the way back to Gen. You may, I dont...its just a difference of opinion based on interpreting scripture. I certainly wouldnt consider it a sin.
I have been informed by the likes of the subect of this posted article that I am a Sinnah for "Not Be LeiveIng GoD's WooiooorD!!" simply because I disagree with their 24-hour creation-day interpretation.
Imposing that belief (with condemning judgement) on those who believe otherwise is, IMHO, sinful.
And building a $25 Million museum on such a flimsy and egocentric foundation is, IMO, the pinnacle of hubris.