It certainly didn't happen, for example, with Mount St Helens in the USA some years ago
Different volcanos, different results. As several studies have shown, the ash from (unpronouncable volcano) last year was rather different to the ash from many other volcanos - it was much more likely to cause damage to anything flying through.
The expert immediately prefaced several statements with "we don't know". Well, dear, if we don't know, how can you present yourself as "the expert; this is a description of someone who does know.
I'd be much more wary of the person who says they do know, as they'd almost certainly be lying. As proven by the number of times I've been stuck in a rainstorm with no umbrella, meteorology is not a precise science - we do not know everything and there are uncertainties. A weather forecast is only a 'best estimate' of what will happen, it's not perfect.
Btw, I'd also imagine that everyone involved is unwilling to commit to cast-iron statements. I remember in the thread on here last year about the other volcano a number of people got quite angry when 'experts' gave their opinions...