Cleon
Legend
You have a "lich" under the "Spells" entry. Actually, do they really need a Spells entry? Vampires don't have them, for example.
Silent Spell would be fun, but it would partly defeat the purpose of the Mute SQ. I think, since they're not primarily spellcasters, I'd let individual shadowrath's choose.
The Silent Spell feat would be very useful (although Automatic Silent Spell would be even more useful...) However, while the text says they retain their original Intelligence it makes no mention of them retaining spellcasting ability. An inability to use Verbal component spells would go a long way to explaining that!
So, I agree to no bonus Silent Spell.