Selling building, tenant breaks lease, can I keep safety deposit?

[Alan M.]

I'm selling a 3 unit brownstone in Boston. I put in leases that required a 90 day notice period but generally treated my tenants well and gave them 5 months of notice so they could get their plans in order as the buyer wanted the building delivered vacant on June 1st. All the units had leases that expired then so it was going to work out fine but one of the tenants notified me on March 1st that they're moving out by April 1st. They're saying they're not obligated to pay for April or May because the 90 day notice period was meant to be for them not renewing, not for me selling the building.

It's in Massachusetts and, according to some Googling, I can keep the safety deposit for non-payment of rent but the complicating factor is that the tenant is 1) a minority 2) a lawyer 3) a town selectman. 

It's only $2500 in security deposit and they would owe $5,000 in rent for April and May. I wouldn't chase down the remaining $2500 but I don't want to have to fight in small claims court, because I live in California and have zero interest in traveling to Boston with Covid-19 out there.