RAW was formed in 1968 from Intelligence Bureau, so RAW obviously did not have a role 1949-1968, but Intelligence Bureau as its predecessor could have. And when RAW came into being under Indira in 1968, I think East Pakistan was one of its major theater of activity.
Please show some sources where it says Mujib's Bengali nationalism included Assam or any other states in North East India. Are you also saying that Mujib thought that West Bengal would join East Pakistan under Bengali nationalism or just Assam? You do realize that Assam means automatically India looses connection with all other states in North East India. So in effect you are saying that Mujib was a lucky chap, as he was thinking that he could use India to get independence and also get Assam and the other North East states as gift from India.
And from what I have seen about these North East states, each have their own culture and all of them do not like Bengali's, including Ahoms and Assamese, who have their own distinct culture. What they wanted always is independence but never to join with East Bengal.
As far as I remember, ISI was involved with North East states insurgency, not Mujib or Awami League.
Well, there were few threads which you probably missed as you joined PDF recently where we discussed pre partition and post partition history.
Just give you few hints.
1) Muslim League and Congress elitist political parties in the early 20th century which never represented the peasantry society of erstwhile Bengal. Muslim League was the party of Nawabs and Congress was the party of Jamindar.
2) Fazlul Haque brought the politics within the reach of peasant class through Krishak Proja party.
3) Communist parties / Left leaning parties also worked along.
4) Fazlul haque did not have mass support from Hindu community which he deserved most.
5) In the Bengal Assembly Fazlul Haque secured more seat than Muslim Leaque.
6) Congress secured maximum seat but did not have enough to form government.
7) Fazlul Haque seeked help from Congress instead of Muslim League to form the government.
8) Congress declined, seeing him as Muslim.
9) Muslim League capitalized the situation and extended support to Fazlul Haque who formed the government.
10) Later as the all India Muslim League got the momentum, Fazlul Haque joined Muslim League.
11) Fazlul Haque supported Lahore proposal with a precondition that Bengal will never be divided. Pakistan or No Pakistan.
12) After the Fazlul Haque Sohrawardy took the charge of Muslim League of Bengal and became the Chief Minister.
13) Sohrawardy had the same view of Fazlul Haque of not dividing Bengal.
14) After the riots of Calcutta, it became obvious that Bengal will get divided.
15) Sohrawardy and Sarat Bose of Congress made the last minute effort to keep Bengal United tried for a United Secular Bengal.
16) Jinnah supported the move.
17) Bengal Muslim League (Hawkish faction) of Nazimuddin vehemently opposed the idea of Secular Independent Bengal.
18) Non Bengali Hindus from Calcutta opposed the same move.
19) Neheru opposed it.
20) At the end it seemed that, too many non Bengalis were involved in securing the future of Bengal.
21) Bengal got divided.
22) Tripura wanted to join East Pakistan after partition.
23) Nazimuddin did not want any more Hindu majority territory in Pakistan fearing to loosen the grip of Hawkish Muslims (Non Bengali).
24) Nazimuddin was more worried about Kashmir than Tripura.
25) Sohrawardy declined to come to East Pakistan before all the repatriation of Muslim from Calcutta takes place.
26) Nazimuddin took this opportunity and kicked Sohrawardy out of National Assembly.
27) Sohrawardy resigned from Muslim League.
29) By 1948/1949, Awami Muslim League was formed by Bhasani.
30) Sohrawardy joined Awami Muslim League in 1950/1951.
31) Fazlul Haque also gone back to his Krishak Proja Party leaving Muslim League.
32) By 1954 it was clearly visible that there were two faction in East Pakistan, liberal secular faction and a hawkish muslim league faction
33) Jukto Front was formed and Muslim League was defeated by huge margin.
I hope you should understand the dynamics of East Pakistan politics by now. RAW was too small of a factor to move stall wart like Fazlul Haque or Sohrawardy.