Quite right. If the HGV is alongside the cyclist, then prior to that the HGV would have been behind him, so would have seen him at that point. It's similar to doing a blindside reverse. When you roll past the loading bay to set the outfit up for the manoeuvre, you have a good look at where you are going to be reversing so that you have a picture in your head for when you can't see. The cyclist may well be in the drivers blindspot as he makes him left turn, but if the HGV has just gone past him, he really ought to know that he might still be there.