I regularly use the children's area at YYZ INTL when traveling with my family. About 50% of the time, I have to kick out adult-only parties who settle there despite there being space available elsewhere. To their credit, the dragons have been very good about intervening when some extra persuasion was needed.

I fail to see how the lounges are exclusively for the business traveler. Per the terms and conditions of the Altitude program, MLL access is granted to whoever qualifies by flying X numbers of miles, plus their immediate family (or to whoever secures access in any number of additional ways). I see no mention of the business traveler in the Altitude rules. If lounges were meant to be a quiet oasis for the business traveler, companions should not be allowed, nor should anyone under 18 years of age. The program clearly specifies otherwise - i.e. AC has decided that children are welcome in the lounges.