And i disagree your thought about attackers redding gates. Before update defenders and attackers both were able to use non-red gates but now only defenders have that advantage, for some servers i agree that only defenders able to use gates but for eu1, definetly not
You can still travel to and from vulnerable clan-owned sites without the Duelist or Outlaw status. It does mean that after one unsuccessful attack you can regroup in a safe area, wait for your combat status to run out and travel where you need.
All vulnerable sites work exactly like attacked (red) sites in the past with a boost for defenders that enables them to travel regardless of their combat status. Thus, on a server with a very active Town hall travelling between sites is less available in general.
Before the update (during large conflicts) players would often use strategies that led to a similar outcome. Keeping sites red as allied defenders for area control used to be a large part of the game and it was enabled by the maps' linear design. The difference is, the players had to spend their Supplies and be ready to "close Travel Gates" at the right moment to prevent others from accessing the map easily. Now the new game mechanics on active servers changed the maps to be less accessible by default, without requiring any input from players.
Red sites became totally inaccessible to anyone, but there are still some ways to safely get access to a map by using the Teleport Matrix.