IMHO anything goes for a random normal. I'd be a little worried if I saw a pet sorc tank in a vet trial, but as long as they have a sword and shield in a normal dungeon then I'd be fine with it.

I've actually done this (tanked random normals on my sorc with a clanfear). My reasoning: I'm trying to level up the Daedric Summoning line, so I need something on my bar before unlocking bound armor and the clanfear can at least provide a heal if needed.

My two cents, if you are using a pet as dps, then clannfear is the wrong morph. The volatile familiar packs a pretty powerful aoe skill and thus is far better for damage.