I don't have specific info, but: Moses Marx is 69 years old and owns a near majority of its stock (49%). His owning $23 million of illiquid stock is not great estate planning. He's thinking that its time to find a merger partner and put his money in place more readily managed and liquidated.
Perhaps $30 is too cheap an acquisition price, but Berkshire may only be an attractive acquisition to a major player already in the NY metro market.
Aren't the bank's major assets that it has been conservatively run and has a U.S. government agency debt-laden balance sheet? It's small (?) customer base and few retail banking properties are not the major attractions.
These are speculations and not based on thorough investigation. I bought stock following the lead of the bank's insiders a few months ago, liking the price action and with a sense that paying 1.1X a solid book value was not likely to go wrong.