I just pulled that warning from the AS5 site...I don't know what the hype is all about with that anyways there are much better thermal compounds out now and cheaper than silver as well
I still don't think its a good idea to use AS5 on top of the ASIC, that could likely be the reason why they have other compounds which are not capacitive ...likely and maybe are just guessing that it wont screw anything up and better safe than sorry I always say...that warning is there for a reason, keeping in mind that not everyone knows how to even apply grease we could assume its likely though