I suspect that is part of it as well, and it may have been better for him to fumble it a little here rather than make any crass statements;
but I also think it would have been possible(assuming he anticipated the question)to allude to the fact that docs know Iclusig was tested in the sickest patients in making their decision about whether to prescribe, and, as they've seen, the box warning issue hasn't appeared to hurt the launch at all so far.
I don't think that would have put either their relations with the FDA or the EMA at risk in any way-merely a more favorable statement(and framing) of the facts.
However, as I said before, no big deal.
Just a bit of inside baseball...