It seems you are right about how the IRS treats the discovery of a treasure:
http://www.foxbusiness.com/features/2014/07/03/found-money-is-awesomebut-must-pay-uncle-sam.html
Steem Power is not a cryptocurrency, @lexiconical mentions something to that effect:
...Steem Power is literally not tradeable.
If I understand the SteemWhitePaper correctly, Steem would be inflationary liquidity, Steem Power the company's long-term capital (vesting), and Steem Dollars convertible notes (debt) making interests. It could probably be argued with the fisc that those three should not be treated in the same way. As to whether or not the IRS would interpret Steemit Inc.'s return of value to its members similarly to what the white paper might suggest, I would say is anybody's guess.
in case people are questioning the source. as someone who's passion is taxation, I'll vouch that the OP was correct in treasure valuation.