Earlier quoted context omitted.
Just a guess, but I think they don't want to serve as an oracle for the people whose malware they are trying to block. Not saying that isn't shit or frustrating.
Saying they detected malware already does that. Being slightly more specific shouldn't be a problem.
Saying "we know you are compromised and know exactly where, but we're not going to tell" is very childish. Now, if they said for a nomial fee, we'd be happy to share the results of our work, would be another thing totally.