Does an investor who declares himself to be passive lose forever the ability to become active? Suppose he comes in saying "hey, I'm going to be a passive inves

Does an investor who declares himself to be passive lose forever the ability to become active? Suppose he comes in saying "hey, I'm going to be a passive investor" and the subtext is "funny you didn't notice me amassing so much of your stock", meaning "I could yet become an active investor and do a hostile takeover". It's not farfetched that management might react to that by saying "we'd rather you become an active investor, and here, you can take a seat on the board if you promise you won't mount a takeover". His intent could have been "passive for now" and mgmt maybe immediately changed his mind. Would that be a crime, or a violation of any kind, or misleading? Would saying "passive" commit him to being passive even if mgmt preferred him to be active? How would other investors get misled by any of this? Couldn't he just as quickly have decided to get out of TWTR and sold his shares, and if so, wouldn't that possibly have done more harm to other investors? What's the law say about this?