Security is always their responsibility and sorry to hear that they said otherwise ??
Go to https://sitecheck.sucuri.net/scanner/ and see if anything comes out.
If Sucuri doesn’t show anything, see if someone from https://jobs.wordpress.net can give you a hand. Maybe this is something simply overlooked.
P.S. Keep in mind that the platform is safe, however outdated plugins or badly made theme can be a problem.