Well, you do not need to have a clan to be able to counterattack... since you can´t see how much gold people outside your faction have, there was the danger for him that you still have enough money to equip your guys and you could just have walked into the village, bought some stuff and attacked the village. (hypothetical)
How should he know that you are new before you sent him a message?
In this case, you have to call half the community in strat "motherfuckers".
Nobody cares whether you are new or a veteran, the fact that matters that you wasn´t able to defend your fief.
If he wouldn´t have attacked you, someone else would, trust me.