NETS translates this into English as “because he practiced deceipt before him, that he might find lawlessness in him and hate” but that’s a literal translation that IMO makes no sense.
I’m wondering if what the LXX author/translator is actually saying here is something like this:
“For he changes his countenance to mask his lawless intention and hatred”
NETS’ English here leaves something to be desired, as is often the case. They mean the English verb hate, not the English noun hate, as most people might read. μισῆσαι is another infinitive parallel to εὑρεῖν going along with the article, “find the lawlessness and hate [it].”
“His countenance” is wrong for ἐνώπιον, but otherwise yes, I think it’s possible that ἐδόλωσεν is meant to be read as an act of frustration of the articular infinitives rather than enablement.
The lawbreaker says in his heart regarding his sin – there is no fear of God before his eyes – that right in front of him [God] he [the lawbreaker] tricked him out of finding and hating his lawbreaking.
Translating the stuff after ὅτι as reported speech.
Hmm, I’m not sure it’s reported speech as I think maybe φησὶν here is intentional i.e. “The transgressor thinks (resolves) to sin” as per LSJ II b.
And I was thinking that αὐτοῦ in ἐνώπιον αὐτοῦ is “self” here, so ἐδόλωσεν ἐνώπιον αὐτοῦ is “he disguises [sense 3 for δολοω in CGL) in front of himself (i.e. his countenance) to hide his lawlessness” and maybe “yet actually hates”.