You are missing the most crucial point. Why cannot Salem group buy the land from farmers directly by paying market price that is agreeable to both Salem and farmers?
This has been allowed by Narendra Bhai in Gujarat. Dozens of SEZs have been set up there with aboslutely no peasant unrest as the corporates have paid very good price for the land on the coastline and the farmers are very happy with the deal.
The Bengal govt. is trying to buy land cheap and sell it to Salem Group at five times the rate it paid to farmers. It is trying to make indecent profit from the deal, and hence the unrest and farmers feeling cheated.
Leave the buying and selling to market forces and Bengal govt. should remove itself as the "compulsory middleman." The whole problem will be solved instantly.