Thanks for that blast from the past, I say, you must be reaching old age, and it's good you cant recount the memories from those boyhood years of 1948.
Come what may, the language issue was resolved in 1956, so to present that as justification for the Awami Leagues 6 points, does not make sense.
No one says that East Pakistanis were not upset about Bengali not being the official language.
Jinnah cannot be blamed personally for this, since he was not even an Urdu speaker himself. He can hardly be said to have prejudice for a particular language. The historical supremecy of the Urdu language, and it's official use for hundreds of years, gave it the best chance of unifying the country.
Bengali, PUnjabi, Sindhi, could not have unified the country. You think Sindhi, or PUnjabi is of a lower value, as a language, than Bengali?
Urdu/Hindustani had been the lingua franca of India, even though those from the south and east of the subcontinent are loath to admit it.
It was also the language of prominent muslim, islamic scholarship, the language of discourse for muslims from different linguistic backgrounds, be they Telugu, Malayalam, Gujurati, Bengali, Punjabi or Pashtun. How you do not recognise this, is beyond me.
None of the early leaders of Pakistan was an ethnic Urdu speaker, so it cannot be said that there was any prejudice in favour of the Urdu language. Even now, in my city, I converse with Bangladeshis in Urdu. Just had a conversation with one yesterday. That is because it is still the lingua franca of Pakistan, India, Bengladesh, Nepal and Afghanistan.