Nowhere on that page does it say they are Canonical employees. Ubuntu wiki is jus that - a wiki. The page hasn’t even been edited since 2015.
If they were Canonical employees, I wouldn’t expect this PPA to last much longer anyway because the entire reason Firefox has been snap’d is so that Mozilla will be handling updates and Canonical doesn’t want to handle packaging it anymore.
Hosting content on a wiki does not automatically grant anonymous the right to edit said wiki. This particular wiki is not open for editing. Assuming an organization uses a wiki would mean content on said wiki is not to be trustworthy is not factual.
The group members and their roles within Canonical is available for anyone to see.
You can see on their launchpad they are pushing official Firefox PPA:s for Canonical. It is updated to this day.
You can see on launchpad this group is maintaining the whole Firefox package for Ubuntu.
Do not use this PPA, it is not trustworthy.