Does ‘legit intel” pass as a usual English word?

Legit intel is not a fixed phrase. It's just a couple of informal words used together:

• legit: legitimate, respectable
• intel: intelligence (in the reconnaissance sense)

I agree with the answers currently posted - "legit intel" is not a fixed idiom.

Interestingly, perhaps, we have a choice:

• "legit" as current slang (as in @Rye's Answer), meaning 'true, pure, or of notable positive quality - though possibly not the highest'. "This is a legit party." "They're not studio quality, but these are some legit headphones for casual listening."

• or "legit" as an abbreviation of the more traditional sense (as in @Brad's Answer) - 'legit intel' as opposed to 'fake, forged, illegitimate intel'

IMO, either fits Dowd's context ...