I know nothing about the Belgian Center for Cybersecurity, but the fact that they are running a platform that has been infamous for its security issues for 25 years, and been considered essentially obsolete for 15 years, immediately makes me not take them seriously.
This is like a Health Ministry recommending leech therapy to its employees.
What platform hasn't had security issues?
Anyway.
CCB is overtly a marketing organization, not an IT security one.
IIRC they don't even host their own website, The Chancellery of the Prime Minister does it for them.