Regulations are made by the Governor in Council, which effectively is the federal cabinet. It's not the individual minister, and it's certainly not the investment review division.
If you figure out what you want to cover and you have a more flexible approach in regulations, the other layer on top of that is guidance from ISED, for example, on how they're going to interpret and apply what's in the regulations and in the law. That's another level. However, in terms of the prescribed business activities, there is greater flexibility if you stick those in regulations.