For the Want of A Comma, the Lonely Mountain is Lost

 

I saw this on social media earlier today and was appalled.

Well, not to that pearl-clutching level, of course. But would Tolkien really forget to put the comma in the sentence "Bilbo knelt on one knee filled with sorrow."?

I have to wonder if I'm overreacting here (thus the pullback from the pearl-clutching). And I also thought, "I'll check in my own copy to see if this is a transcription error. So I looked and found this:

So either this is a perpetuated mistake, or the sentence

Bilbo knelt on one knee filled with sorrow.

doesn't need a comma, thus:

Bilbo knelt on one knee, filled with sorrow.

If it were me writing the sentence, I'd use the comma. But commas, in my mind, are mysterious objects and I often find I overuse them (except for the Oxford comma; I'm a big supporter of the Oxford comma).

So what say you? What say the rules? I need a ruling, or I may not be able to get to sleep tonight.