Realising the truth, ants are most hardworking creature on this planet. They also are hygenic /clean creature which will not destroy my laptop and I know it. Also so far, there is no news or nothing related to ants spreading any kind of disease. Ants are common. You are reacting to ants like those are some huge pandemic spreading illness or any kind of virus.
Speaking truth, I do not care if they are spreading any virus or anything but what I am ONLY concerned is about taking them out from my laptop forever.
I lost a digital camera like this. To me its not a joke, and i can't even imagine why they chose it as a nice place to make a nest... In fact the queen decided to use the flash as queen chamber, so it was perfectly visible once you took the camera out of its fabric bag where i was left for months unattended.
Ants may be clean, but they are also somewhat conductive. So they start crossing things with different polarities causing little shorts here and there. Often their bodies keep piling until they can make enough current flow the wrong way and damage something.
So no, its not harmless, you should get rid of them.
I never used laptops on the lap, because i find that incredibly uncomfortable (besides fabric is bad for cooling).