Insiders are prevented from buying/selling compa

Insiders are prevented from buying/selling company stock when a material event is known to them. A few bashers are pointing out lack of insider buying at these low prices .... but if they insiders are prevented from buying can this also be construed that a material event is imminent. Just asking for a friend! {{{LOL}}} Just a novice on this topic, maybe someone with more knowledge can explain this better.