You should read more, like the company's own website.
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.
I'd also wager (although admittedly I didn't bother looking for the source you are sighting) that the designers didn't test conductivity at the voltages that we're talking about in these amps.