The problem is proving it. SIRI was probably due for a corrective drop and support test anyway. If Liberty felt like the price had gotten too high to buy more (and they planned on buying more shortly but only if the price came down), what is wrong with suggesting to an analyst that the price has gotten too high and asking the analyst to look at the stock after doing some research and post an opinion? Of course if liberty paid the guy to post a sell and run opinion and paid him to post the sell opinion, then it IS a big SEC issue!
If the price was not too high, then people would not have dumped and run the day that analyst said it was too high (the day they killed the price over $1 rally to keep it Nasdaq listed). IIRC I think he said the stock was worthless or some such BS.
I just know it is easy to buy and a hold a good promising stock, watch the price collapse, and then suddenly a savior comes in and takes it over for pennies, locking in the buy and hold investors losses permanently. I have been screwed that way far too many times since 1986, to buy and hold most stocks anymore.