The adoption of the Lebanese dialect as the country’s official language and the promotion of the Lebanese language as being independent from Arabic is purely on the basis of convenience.
Bosnian, Serbian, Montenegrin & Croatian are all just versions of the same language. Hindi & Urdu are mutually intelligible as spoken languages, to the point that they’re sometimes considered to be dialects of a single language.
“Lebanese” is the culmination of thousands of years of linguistic evolution in the Northern Levant. Languages change and identities change. Nationalizing our dialect with a Latin script would make everyone’s lives 1,000 times easier.
All this being said our dialect can definitely qualify as being a separate language considering the substantial amount of Western Aramaic influence in our day to day language, with some Turkish and French.
I’d even be down for a shared “Northern Levantine” or “Syro-Lebanese” language with a Latin script. Either one works just fine.