What's important to understand is that Health Canada, just like anyone else, can interpret the act however they deem reasonable. You could have a different interpretation of the act. Health Canada could be wrong, you could be wrong, or you could all be wrong.
What's important about what Justin has said, is that if true, it would seem to indicate that Health Canada has landed on a particular interpretation of the act going forward, and it is apparently one that includes certain portable lasers as dangerous goods. Justin is indicating that Health Canada plans to henceforward continue as if high powered portable lasers fall under this act.
Now, if you disagree with Health Canada's interpretation, you may or may not have some ability to challenge it in court if Health Canada acts on its interpretation. I don't know - I haven't read the act to know what mechanisms are prescribed by it. But the point is, if you don't want to be in that situation, you need to conduct yourself in accordance with Health Canada's interpretation. If you have your own interpretation that tells you otherwise, then you'll likely need to argue it (in court). That's not a scenario that I would encourage anyone to put themselves in.
Lots of regulations require interpretation, and that interpretation often happens by government bodies. That's fine / legitimate. This article says that it is in the process of being updated, and I would imagine that it will give some clarity on the Health Canada position once it has been so updated:
It's Your Health - Laser Pointers [Health Canada, 2004]
Not legal advice ^. Just my gut on the issue, not having read the act.