Of course, if he is still completely alone, he is still not very dangerous!
But i can't say more as long as i don't know what you did with the rest of the Boss room.
-----door------
is (a lot lot lot) more dangerous than
-----door------

That said, a single Orc is not very dangerous. Your Boss Orc was taking maybe 2, maybe 3 life points.

Did you really pit him alone against all the Heroes?
To be exact, my calculations predict, for a SINGLE Hero with AT3 DE2,
an Orc would do 0,32 BP damage (nearly not measurable) and an Orc with 8BP would take 5,7, more or less like your Boss Orc.
You can divide that then by anything between 1 and 4 for an entire group, depending on how good your Heroes work together and how many friends your Boss orc has around him.

So we come out at something between 1 and 6 final result. If he was alone against all Heros, it is more about 1 BP loss. Dangerous wohoo.
Well, Count Mohawks Questimator predicts us solid 8 Body Point loss for the entire Quest of Sir Ragnars Rescue, and properly used, it is quite exact. It has the advantage of calculating entire Rooms as it should be.
Your Heroes have 2 Healings and 25 Body Points, so the Quest is far from dangerous! That's why i said they have "marge" left.
Final word: Any Monster works best with 3 or more body points. If you ever think about a uncommon Boss Monster, give it 3 Body Points or more; no matter the rest. Do the rest "by feeling".