Ann: Change of Director's Interest Notice-SRX.AX, page-50

There is very little to no correlation between insiders selling and future share price.
Yes research has been done on the subject.

They sell for a myriad of reasons.

On the other hand, when they start buying gives a very bullish signal to the market.

I am not bothered by the selling. I have seen many times in the past when a director sells then SP a year later doubles or even triples. I held Blackmore when Marcus Blackmore sold 150k shares in March 2015 when the SP was less than $50 just before the SP started going really bonkers. He sold to pay off debt and buy a yacht.

You could also reasonably argue that if Gilman knows how the business is going then it much more likely he is selling because it is going very well then the opposite.