I say that it's not a shooting attack - because it's not one! To be a shooting attack it must be called as such, the Lord of the Storm ability does not. It really is that simple, and anyone arguing otherwise is also arguing against the other Doom of Malantai example given (to add one, Epidymius' area of effect ability as well).
But, let's say that you're right and that the ability is a shooting attack. For it to do so, it must either use Imotekh's
BS or hit automatically. So the Snap-shot from Hard-to-hit kicks in and the shot is then resolved at BS1, which hits on...
...a 6.
About the only possible counter to this I can see is if the attack hits automatically, it cannot use a
BS. But it's Imotekh's ability, he has a
BS that can be replaced. If you're arguing that it doesn't say it can use his
BS... why can't it? You're telling me it's a shooting attack, and the ability doesn't tell us that we can't use the firer's
BS.