First of all, that QSC amp has external cct breaker on the transformer primary side and fuses on the secondary side. Secondly, I am quite familiar with various CSA codes, I have to, by profession; and your are correct that I am not aware of such CSA requirement of "a thermal breaker inside the primary power transformer"...
Actually I don't what you mean as there is no such thing as primary power transformer, unless you mean to say the "primary side" or the "primary winding", in this case the 120 V side (North America standard). In that case, it is possible to have an embedded sensor, such as a RTD that will activate an external scheme based on a contactor and/or breaker. I doubt this is common practice and most would just use external breakers and fuses. In any case, i highly doubt it is mandated by CSA. To comply, you just need to follow the relevant sections of CSA C22.1, C22.2. I have the standards but I don't memorize the contents. So if you know that for sure, please post a link or the section number of the standard. Thank you.