I think if there was a sudden movement of any of Satoshi's coins it would create the following (overlapping) fears:

(a) Satoshi is planning on selling (b) Satoshi believes its over-valued (c) Satoshi doesn't agree with direction of project any longer (d) Satoshi is not active, but there has been bug found, nothing is safe. (e) Satoshis presence will become politicized by competing groups (ie. Snowden, Assange, etc) (f) Satoshi is alive and will be arrested, co-opted, killed, kidnapped by state

None of those overlapping fears would be easy to quell, and would exist simultaneously to various parts of the community, thus I think a panic sell situation could emerge.