I think we need more information to decide whether this is the usual LM (make them cower into submission) type witch hunt, or whether it is a genuine attempt to clean up on apparent stock market manipulation.
(I've have already expressed my opinion of what a stupid situation it is where rumours of the health of one aged person, who has nothing to do with running any company or country, and is 'above' politics, can have such an effect on the stock market)

-Does anyone have more details of the particular web forums these alleged 'manipulation' rumour comments were posted on?
-Were they on stock market investing sites, or political sites?
-What other types of comments did those posters make (ie are they mainly discussing politics or stock market investing?)
- Can those individuals, or their family's, be shown to have profited by the 'rumours'?

Knowing the general paranoia and attempts to limit free & open discussion of 'you know what', I would not be surprised if the authorities are motivated by something other than what StanG seems so concerned about.

btw, With all this spying & blocking going on, there's little wonder the internet is often so slow in Thailand!