Can you explain? How are they able to check whether someone did a quick “in and out” keylogger or cookie extraction? I doubt they can, because I doubt they store every request (that would go against what they claim for privacy) and I also doubt their DB backup happens on such a high frequency that they could catch this (e.g. minute-to-minute).
So…how? Are you claiming they have oodles of logs and a perfect dork* to find suspicious JavaScript? If they had the latter wouldn’t they already be using it for security?
If you have some method that works do tell.