I sent a couple emails to them around the time Musk labelled them as state propaganda. They sent one reply back saying they'd forward it to whoever is in charge of social. No way to know whether or not is was just basically flushed down the toilet though. I don't know if there's a particular way to reach them to recommend that they set up a presence here.
I don't really see the downside for them. A private server would be relatively low cost and it could be hosted on servers they control in Canada. Beyond an official place for their work, it also means their employees and journalists wouldn't have to worry about where to sign up, plus give them instant account verification.
As much as I love the CBC, they always seem a bit too reluctant to lead.
Edit: Just wanted to add that it's important to reach out to CBC any way you can. I'm not sure about other Fediverse projects but Mastodon at least uses Rel=noreferer in the header. Traffic from Mastodon users will show up in analytics as direct traffic so they can't see how many people are originating from there.