I was missing that the activation options were a sequence. Kept looking for explicit rule. It becomes quite clear when you look at Tactical Action sequence.
thanks for response.
If you thought the sequence could be any order, why wouldn't you think the Space Dock could build a fleet before the Space battle?
Expanding on what Alan said, infantry produced by Saar space docks or any other production unit in Space can be placed on friendly planets or ships with capacity.