Of course the devs care about this. Apparently this guy has discovered a "loophole" in the mining algorithm that enables him to outmine everyone else. @abit or @arhag can explain the technicals if they want, but anyway they already see a fix so the loophole will be closed.
What's cool about this is that it means some very smart minds are looking at the algorithm, which will only help it grow stronger.
Hats off to mr. supercomputing :)
@rainman, Is this consider a 51% or 99% attack? and can he hijack the blockchain?
No, it's not possible for a miner to hijack the steem blockchain as miners don't generate a large enough number of blocks in a round (Steem uses hybrid POS and POW for block creation).
Is the PoS part based on Steem or Steem Power holding?
I see. Thanks for the answer @blocktrades.