It depends.
Was it restricted or nonrestricted stock.
If it was restricted, there was a From 144 filed. What date was the form filed? It could have been filed before SeeBS ran with the 60 Minutes story.
If it was nonrestricted, a From 4 was filed.
Does Sumner Redstone have a habit of regularly selling Viacom shares? Probably.
The same mistake can't be made that SeeBS made. A lot of investigation needs to be done before anyone can claim Redstone's sale was inside information. Also, the SeeBS story became public information so you can't say there was inside information, otherwise you would have to say Redstone knew the story was bogus and SeeBS would take it on the chin. I highly doubt that is what Redstone was thinking before the story ran.
Besides, Viacom's stock has been sliding since the spring. Executives get a lot of stock. Usually, the stock exceeds the monetary pay in dollars. That means that executives are constantly selling stock of their companies.
Studies have shown that there is little positive correlation to long term insider stock sales to the price of the stock. Indeed, there is some negative correlation meaning that long term continued selling by insiders usually occurs when the price of the stock is rising.
Trying to pin Redstone's stock sale to the SeeBS story is barking up the wrong tree, in my professional Series 7 (NASD/SEC) licensed opinion.
Look at the date of the transaction. I believe it was September 14. He may have needed the cash to pay his taxes on the 15th.