I think it was meant for a FP use, to protect your allies from Dunlending Warrior and Dunlending Ravager. Not a Shadow use to block allies from fighting.
If that's the intent, I still think it's a bum site. The only real way that this would be useful is in a 3+ person multiplayer game for the shadow player playing the site to also have
allies. Rohan has no way to play the next site by itself, so the burden will fall on the shadow player. Of all the site 3s in TT for a player to want to go second for, this is bottom of the list.
Further, as someone who thoroughly enjoys tacking
War Club on
Dunlending Warrior, I would just wait until the next site to play that minion. 90 times out of 100 the free peoples isn't going to be able to push past the 3rd site in the first turn, and 9 of the other times they're not going to choose to.
If it's a card for the Free Peoples player, I'd call it far worse than
Meduseld. If it's a card for the shadow player to block
allies from skirmishing at their home site (and it would've been a good one), the allies likely had their home moved from 3 (their home) to 4 (when they were vulnerable and forced to fight, during the journey from Edoras to Helm's Deep) later in production and this card was left out.
But perhaps it was neither of these. Based on cards like
Ranks Without Number, ally skirmishing was a problem they were looking to build in-game counters to rather than ban cards (The first round of bans, which included Boromir's Horn, was at or around the release of set 5). I think it was to prevent a
Horn of Boromir+Rohan Allies deck from getting set up too quickly.
Think about that - a horde of
allies with access to all the tools of Rohan and bearing
Armor or
Heavy Chain, a mount,
Sword of Rohan or
Rider's Spear,
Rohirrim Helm, etc. Because they're not unbound, they have no fear of Grima, and Boromir would allow at least two of them skirmishing every turn and get healed the next with
Well Stored. With that in mind, I don't think it's a coincidence that
Dunlending Ravager will have 7 str against a
ally - enough to tie with an ally with Boromir's Horn, but not enough to overwhelm one that hasn't been buffed.