and performed an emergency descent to FL350
Perhaps the wrong choice of word in the report, but suffice to say, if they had the other aircraft on TCAS and were experiencing uncomfortable continuous rough ride, they chose a valid option. It is not really something I would expect to see reported in the media.
If you define discomfort as half the passengers barfing in continuous rough ride, as opposed to the shock one single, violent CAT-turbulence, I can imagine that they just had enough of the ride eventually. Atlantic weather systems are not pleasant by any means.