Sax,
I disagree.
Yes a chunk of reverse duct had fallen off.
But the aircraft was airborne, and at some point was going to have to descend and land. That descent and landing were not going to be any more risky in Dubai than in Moscow.
Therefore, the only saftey related question was, was it any less safe to cruise for five hours before making the inevitable descent and landing?
The damage was done, parameters were stable, and there was no sign that the situation was deteriorating. What is it you envisage might have happened in cruise that might have led to an unsafe outcome, bearing in mind the aircraft had numerous diverion options en-route HAD anything gotten worse?