jIH:

bIvoqbe', 'ej muSuj
you don't believe, and it (this fact) disturbs me

SuStel:

What you're really doing is bIvoqbe' 'ej muSuj 'e'. This is, of course, not allowed.

I understand your reasoning, and it convinces me.

But doesn't this reasoning mean that the {tlhIngan maH! taHjaj!}, is
wrong too ? Isn't the {tlhIngan maH! taHjaj!}, actually {tlhIngan maH!
taHjaj 'e'!} ?

I know that it is blasphemous to dare and question something which has
been celebrated as a feat of linguistic ingenuity.. I really do. But,
- holy sith ! -, I'm sure as hell, that if a mere mortal had come up
with this phrase, he would have been executed on the spot.

tlhIngan maH taHjaj is (a) a slogan, and (b) not canonical. As a slogan, it's not going to be careful to ensure everyone knows what the antecedent of its elided pronouns are. As a non-canonical sentence, it's not a data point in what can and cannot be said.

Now, I have no doubt that Okrand will canonize tlhIngan maH taHjaj the first chance he gets, if he hasn't already and I don't remember. There's nothing ungrammatical about it; as with your sentence, you can assume the subject of taHjaj is an elided noun, like ghu'vam or something. I suspect it doesn't matter in the same way that the subject of SIS doesn't matter.

Everybody keeps acting like I'm passing down an an edict, but I'm not. You asked whether you could say bIvoqbe' 'ej muSuj, and I said it's not ungrammatical. I questioned whether you really were eliding a ngoDvam or if you were really just eliding an 'e' and not admitting it to yourself.

And I still think muSuj voqbe'ghachlIj is the best translation of the line.

-- 
SuStel
http://trimboli.name