I've played several games today against Fiddle, and his crow silence locks me out of all summoner abilities.

Is this an intended mechanic? I remember seeing something a few months ago from a red poster that implied it wasn't.

From a theorical point of view they shouldnt get silenced. Since those spells are used by "the summoner" and not the champion. The summoner being yourself as an omnipotent presence in the game that tells the champion where to move and what to do. But, the main problem with this is that if you can cast them when silenced/stunned then you could always flash away. Even when stun locked etc.

Silence and Stun breaks the communcation link between summoner and champion meaning you can't use summoner spells. Only cleanse can be used, as its strong enough to break through this barrier and restore the link.

Thats the lore, from what i've heard anyway.