Reassuring, though it'd be more so if they specified a threshold at which their counter measures kicked it. Say, 40%. They only say that they'll avoid reaching 51%. Does that mean they'd be comfortable at 49%?
There's not difference for us between 40 and 49%. As long as they do not reach the 51% we are safe.
The real problem is that even if they allow users to mine from other pools, they can just switch back in every moment. That's a potential persistent threat, altought i don't think they are so stupid to really try to perform a 51% attack : that would be a suicide for them....