But having said that, Blockades can only be done by ARMY figures not scouts. So both would have to be on the tile at the same time to be able to blockade and return the CULTURE not anything else.
Not true, scouts can blockade as well.
Rulebook Page 14 wrote:
A square in a city’s outskirts that contains one or more enemy figures (either scouts or armies) does not produce trade for the city’s owner. For full details on this, see “Blockades” on page 27.
Rulebook Page 27 wrote:
Enemy forces, properly placed, can prevent a city from obtaining some of the supplies it is used to obtaining. Thus, a square in a city’s outskirts that contains one or more enemy figures (either scouts or armies) does not generate production, trade, culture,coins, or resources for the city’s owner. A square may be blockaded even if it contains a building or a great person.