I would imagine that the value of the pension for the purpose of calculating the 2018 RMD under these circumstances would be the amount that would have been be rolled over to the IRA had the pension buyout occurred on December 31, 2017. Similarly, the RMD for 2018 would be calculated on the value of the pension buyout had it occurred on December 31, 2018. However, I don't think there is any specific IRS guidance on this.
