A company may decide whether it will move or not at
almost any moment of organization phase.
At the
end of organization phase it is definitively known whether a company will move, or not (hence "
almost").
As it has been noticed a terms "moving"/"not moving" are used inconsistently. A company is always in one of states - "moving" or "not moving".
Additionally in organization phase "moving" may mean "that decided to move", "not moving" may mean "that decided to not move".
It may be easily deduced that "moving company" as active condition of card playable only in organization phase refers to "company that decided to move" and not to the state of company.
"Not moving company" in organization phase may mean "company that decided to not move", or it may mean any company - because each is in "not moving" state (even a company "that [already] decided to move").
The check for "not moving"
state in organization phase does not make a sense (at least as an active condition*), as well as explicit check for existence of a company. Both are guaranteed to be always positive.
Conclusion:
"is not moving" in text of Hide in Dark Places is either meaningless, or it means that Hide in Dark Places may be played only on company that decided to not move.
In second case it is not necessary to demand a playing of the card only at the end of phase (because it would not remove actual problem which is ambiguous use of term "not moving"). Such demand is also invalid (unless someone wants unrelated errata), because at the end of phase only explicitly allowed actions may be declared** .
P.S.
Probably it was not easy just to write "will not move", instead "is not moving" before sending to print.
*) in result of effects of some cards a company may be in state "moving" also outside of M/H phase. But this state lasts momentarily; it is not possible to declare anything during this (infinitely short) period. Some "discard" actions have "moving company" as their passive condition. "Discard" actions (caused by passive condition) happen immediately, not in chain of effects, so they may work.
**) it is debatable whether such action may be responded by other, not explicitly allowed, actions.