I do not know where the idea that HAN is safer come from. I do know that the people who made HAN have recommended using HEN instead. Even if you do not need homebrew, fan control and easy access to the file system are well worth the upgrade.
I think it comes from the fact that HAN offers less surfaces overall to detect hacking for the servers (PSN or Games) you connect to.
There are no custom syscalls, no kernel modifications either, we know it is one way to get flagged by game servers. And even if there are homebrews to help with that, you only need to forget to disable custom syscalls just one time before online gaming to risk exposing yourself to a ban. Never mind the number of people who don't know how to protect themselves or even that they need to if they game online with a hacked console.
Of course strictly speaking, as the situation stands, all ps3 hacks like HEN, HAN, CFW are easily detectable one way or another if s#ny chooses to implement appropriate code to take care of it.
If you take HAN for instance, a quick check in userland memory can tell whether it's enabled & a file system check can tell whether there are any customised files on the hdd or in Flash memory, a quick signature check of game files can tell whether the games are resigned.. Hell, even a simple Internet history check could lead to detection..
If there is a will, there is a way, that kind of thing..
Somehow I don't think s#ny or game servers ever really bothered adapting their code to detect HAN or HEN in particular. I have a feeling that it's still the old stuff targeting CFW that remains in play today.