Not sure why it really matters that the directors don't have a substantial share position, as I don't believe that a single one of them would take part in something as underhanded as you are suggesting. As you may have heard, there is a regulatory body that investigates such underhanded activities, including lowering the SP for personal gain.

You may also have a look at the insider track record. You will find that directors have bought shares recently at much higher prices than current.

Conjecture on motives of the directors is fine, but you are walking a thin line with slander. Please tread carefully.