Yes Jinnah is very complicated figure, just like most of the contemporaries of the political movements of that time period.
It is long conversation I have had with folks like Joe Shearer and Saiyan. As well as many other wise Indians and Pakistanis in whatsapp groups I am part of.
The basic issue is the state was created as majoritarian-religion principle (for the Muslims of the subcontinent, where they were in majority).
Jinnah never shied away from this after his breakup with INC. He was congress party person originally, many forget...and held a fond protege identity w.r.t GK. Gokhale:
https://www.thenews.com.pk/tns/detail/562382-jinnah-naoroji-gokhale
The breakup was due to (among souring personal and trust relationships that were fraying with other congress leaders) issue of separate electorate and minimum representations federally and so on (all on basis of religion).....that he was acting as interlocutor for many other muslim groups with the INC (who it was felt at the time were the apex of progressive self-rule movement from the British at the time).
He did have long term vision in some quotes where religion would become less relevant for Pakistan in the long term....but it stands in contrast to many other quotes he has also made (often brought up by subject matter experts like Ishtiaq Ahmed). Secularism cannot revovled around just one or two quotes (and ignoring the context why they were made).
What his feelings would have been w.r.t the flawed objectives resolution compromise (that many argue is the original sin of the Islamism in legal ideology and larger praxis that has since grown and expanded especially under Zia admin) put forward by the constituent assembly is of course unknown, as he passed away....and as you note his political power was and would have been limited whatever the constituent assembly proceeded.
It is schrodingers cat situation given his conflicting statements (they all have to be looked at, rather than selectively picking) and the fact he convened this constituent assembly (and knew well many of the legal minds within it and their positions)....they saw themselves as equal stakeholders to Pakistan's setup under the overall guidance of Jinnah.
It is all incredibly different to Ataturk. Ataturk saw religion was a poor binding glue given his experience with the Ottoman empire. Turkiye was not made a homeland for Ottoman empire's muslims (many co-religionists undermined and rebelled against Ottoman authority). It is almost an inverted raison d'etre used in Pakistan's proto-state ecosystem (to assert against INC especially as things came to a head in the 30s and 40s).
This is why Ataturk picked staunch secularism as the republic's founding (there was never any doubt, the equivalent of the constituent assembly were told in no uncertain terms it would be part of basic law/article of the consitution iirc)....and Ataturk was closely involved in the early republic for many number of years and wielded considerably political power to set up modern Turkiye's "breakfast" so to speak.
