～ないなりに

I'm playing a game and encountered a dialogue line that I don't fully understand. Context: the player character received sword fighting lessons from リリ in the past (but never actually managed to beat her). She eventually moved away, but he kept practicing the style that she taught him. Now he's visiting her again at the base of the 騎士団 that she joined since then. Upon hearing that the player stuck to リリ's style all this time instead of joining a local 剣道部, the 団長 jokingly makes a crude remark:

[団長] おまえさんはずっと、ただリリのあの小せえ色気のねえ尻を果たせねえなりに必死こいて追っかけてたってわけか

I'm guessing he's implying that the player kept imitating ("running after") リリ because he was, ahem, "missing" her (even though they're not in a relationship). I don't understand it completely though:

• What does the なりに mean? It's probably one of these, but which? I reckon it's 4㋓ since the ない in 果たせない is a 助動詞 in 連体形 (right?). Is this correct?
• What does こいて mean? Is it based on 放く?

1)
It's 4－イ 名詞または形容詞の連体形に付いて、…それに応じて、という意を表す。「狭ければ狭い―に住むしかない」. ない is treated as an adjective.

2)
Yes, it's #3 何かをする意の俗な言い方.

ああ、びっくらこいた ＝ びっくりした。
いい年こいてそんなことするな。 ＝ いい年して
必死こいて ＝ 必死になって

Thank you. From what I read I thought that ない is an (auxiliary) verb, not an adjective, when used as a negative verb ending - but apparently there's more to it than that. Maybe it'll be better to just pick whatever 連体形 option is the most semantically suitable from now on

I wrote "it's treated". ない conjugates as an i-adjective, and expresses more likely a state, rather than movement or action.

It's 4－イ 名詞または形容詞の連体形に付いて、…それに応じて、という意を表す。「狭ければ狭い―に住むしかない」

A dictionary is not always perfect (or, always not perfect). The use of this pattern is not limited to 名詞または形容詞の連体形
You can find such examples as
批判するならするなりに～
経済格差があるならあるなりに～
on the net. The latter is a state but the former is not.

I was talking about the characteristics of ない, and not a requirement of the word preceding なり, but anyway, it doesn't matter whether the negative form of verbs is a verb or an adjective if verbs also can be applied to the definition, after all.

Hoge said:

A dictionary is not always perfect (or, always not perfect). The use of this pattern is not limited to 名詞または形容詞の連体形

Click to expand...

That's good to know, thank you.

Toritoribe said:

it doesn't matter whether the negative form of verbs is a verb or an adjective if verbs also can be applied to the definition, after all.

Click to expand...

If the scope of the pattern covers both ない interpretations instead of just one like stated in the dictionary, that indeed makes things easier