It will all remain exactly as it is now, except for the case when they recognize a visitor that is likely to have downloaded the malware. In this case they should throw an extra warning.
You would be right if nobody besides the affected people would ever know that they are doing this.
But as soon as other people know or hear of it, they will go check the website to "see if they are affected". Even if the website has a huge disclaimer telling people that they could still be affected, the absence of the warning would still suggest that they are not affected, even when they could be.
But as soon as other people know or hear of it, they will go check the website to "see if they are affected". Even if the website has a huge disclaimer telling people that they could still be affected, the absence of the warning would still suggest that they are not affected, even when they could be.