I think the bigger concern is that if there are other foreign influenced MPs who aren't listed in the report, then they and the country influencing them realize that CSIS/Canada doesn't know about them. Keeping it vague and uncertain makes it more likely that those people will be concerned and may reduce their interference to avoid detection.
Likewise, revealing which MPs are known to be influenced may reveal moles or informants that Canada has, thus curtailing future efforts at limiting foreign interference.
"Party of the people" guys, I promise