Seattle and Oregon have both created a precedent covering players attempting to "block" locations with their bodies. This has been in place verbally for a number of years and I wanted to make sure it was clear in writing for all players.
It is perfectly acceptable to use in-game means to block off a location. This may include (but is not limited to) Wards, Wizard Locks, Circle of Power (even in an odd shape if needed), Wall of Force, or OOG safe physical barricades if/when allowed by Plot or Marshals (this last one, of course, can be similarly disassembled when placed).
It is also acceptable to attempt to create a barrier using a player's body in some situations. This will often include a Prison spell, for example Prisoning a player in front of another one who is refitting armor to take packets for them.
In the case where a player's body is being used to attempt to barricade an entryway or portal, a player is free to attempt to do so, but must accept that they can be asked by a Marshal and/or Plot representative to move a minimum safe distance for safety reasons. For example, going into a "starfish" pose and Prisoning/Pinning oneself in a doorway to block it may create safety issues, and such a player may (or may not) be asked to move as appropriate. The same goes for any narrow location and any player whether IG or OOG (for example, you probably shouldn't use a permanently dead corpse represented by a player to "plug up" a hole where creatures keep coming out).
If a player attempts to create such a barrier with their body, they must accept if they are asked to move back for safety reasons. IG a creature could wriggle past someone's arms and legs who is blocking a doorway, but OOG this is an inherently unsafe situation and to reflect that the player who has blocked the doorway may be asked to move a full step backwards (or whatever is needed to make a safe situation). The same goes for players attempting to physically block a Portal, Planar Gate, or other location with their bodies - you may make the attempt, but you must accept a request to move back for safety reasons to let other players move by/emerge/fight/etc. if asked.
-Bryan Gregory
Alliance Seattle Head of Rules