Why would it be? It's a spell, so naturally it's not going to be usable while silenced. (Cleanse was never usable while silenced either)
It's the main way Ret closes the gap and for a melee, Ret is more susceptible to silences than any other melee because we rely on healing spells. It's not like Emancipate removes multiple effects, either. It only removes a single effect.
Haste? Your target uptime, especially vs ranged, is dreadful. Mastery is much better for pvp.
You should be using SS in advance, and making sure it doesn't drop off. An absorb shield is hardly useless.
Haste improves everything we do. Faster casts, more censure ticks, shorter cds on our ranged and melee abilities. Crit and mastery are a preference and more dependent on your comp and strategy. The longer a game goes the better crit is as it also effects everything we do while mastery does not.
I like a balance of both so I just don't reforge one to the other.