Depends on how the game classifies the abilities, sometimes they might seem like spells but are really abilities and viceversa. Just like how the lamb's summoning in AK can't be silenced because it's an ability instead of a spell, probably works the same in PvP for SMN/SCH Summon abilities but I don't really PvP. That's also another thing, a bunch of extra ability effects are really focused towards PvP instead of PvE, like the reduced healing from Disease or Storm's Eye when very few enemies self heal.