This quote is from the Artic Silver website: "Not Electrically Conductive:
Arctic Silver 5 was formulated to conduct heat, not electricity.
(While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)"
So you should try to remove it before it starts to dry out. The reason a high % alcohol is recommended is that it will dry quickly and not leave any water.