If it's short term and small enough that Boston would stay under the tax, then I think it's pretty likely Monty will end up signing with a contending team for similar money.
Unless it's literally his only offer - which I doubt - I don't see any compelling reason why he'd take 2/$40m from Boston instead of similar teams (similar to the Yamamoto situation but lesser dollars, obv).
The only way I can see him settling for a short term deal from Boston is if it's literally all that's out there. Which I suppose is possible, but based on at least loosely reported interest from Texas, St Louis, Philly, the Yanks and the Cubs, seems unlikely. All of those teams are much closer to contention than the Sox and would ostensibly at least be similarly capable of absorbing a short term / low dollar deal (would have to be around $20m for tax purposes, I think).
That said, I'd adore it if the Sox came in with the
@CR67dream suggestion of (I think) 5/$110m and dare Boras to turn it down. But, unfortunately, I don't think there is any chance the Sox offer anything approaching that.