The epithets were originally listed as chuvmey and not as nouns. However, here are a handful of stanzas from the paq'batlh where petaQ is clearly used as a noun -- taking noun suffixes, and being used in a sentence as a subject or object, like a noun.

jach veqlargh jatlh
     muqaD vay' 'ej ghe'tor 'el porgh
     nuqDaq ghaH petaQ'e'

He screamed: “Where is the p'takh
     Who dares to enter Gre'thor
     Within a body?!

(PB, p. 106-107)

petaQvam vIqopbej
     QIt ghaHvaD yIn Hegh je vIghojmoH
     'ej 'oy' SIQ ghaH

I will bring this p'takh to justice
     And teach him life and death,
     The slow and painful way!

(PB, p. 108-109)

nItlhejbogh petaQmey
     tInuD chaHvaD
     nIb yan wIjwI' jan je

Look at these p'takhs at your side,
     They don’t know how to distinguish
     A sword from a plough!

(PB, p. 142-143)

petaQ'a' SoH
     bIlay'DI' qaHarbe'
     quv HIja'chuqQo'

You dirty p'takh,
     Your word means nothing to me,
     Don’t speak to me of honor!

(PB, q. 156-157) (Also, an interesting example for the "prefix trick with type-1 verb suffix" canon.)

In a noun-noun construction, I imagine it would work just like any other noun. A petaQ 'orwI'vam would be, in the most nonspecific sense, this pilot who has something to do with p'tahks. Perhaps the pilot is themselves a p'takh, or maybe their passengers are exclusively p'tahks, or perhaps the aircraft they pilot is a p'tahk somehow. If you are currently angry at the pilot, it would be clear from context that you're probably calling them a pilot who is also a p'tahk. You could also phrase or interpret it as an appositive phrase instead: "The p'takh, this pilot, did such-and-such..." Also, petaQ wouldn't be an adjective. I think the grammatical term is "noun modifier" or the like. But I know what you meant.

I think it's probably fine. We might learn that Klingons would phrase it differently, but I think the point would still get across. (Precise grammar is not always at the front of your mind when you're really angry at someone...)