I'm sure the engineers knew exactly what would happen. It doesn't tell us much about the control problem that we didn't already know.
OTOH, if this wasn't an intentional PR stunt, that means management didn't think this would happen even though the engineers presumably knew. That definitely has unsettling implications.
They knew something like this would happen. Their attempts to stop it failed and they heavily underestimated the creativity of the people they were up against.
http://www.wired.com/2016/03/fault-microsofts-teen-ai-turned-jerk/
Could this be a lesson for future AIs? The AI control problem?
[future AIs may be shutdown, and matyred..]