/execute not obeying the gamerule commandBlockOutput false rule

I tried the new /execute command by doing:
execute @e[type=Snowball] ~ ~ ~ summon ThrownPotion ~ ~ ~ {potionValue:16428,Riding:{id:Creeper,ExplosionRadius:0,Fuse:0,ignited:1,Invulnerable:1}}

And

kill @e[type=Exp]

They both showed messages like: http://prntscr.com/2sczut

I have not done extensive testing but that's what i just found so far.