The thing is, I don't really know what the Red Sox can spend. I'm pretty ignorant here.
We know they are the listed, what was it, 4th on the Miserly Index (spent the 4th least amount of their revenue on their roster, which is absolutely unacceptable given the ticket prices and the devotion of New England fans). Maybe this was an interstitial phase, and now they are ready to spend. If The Red Sox became the last team on the miserly index, spending biggest share of their revenue on their roster, what would that look like? How high would their payroll be? (Though I understand wanting to avoid luxury tax penalties, or avoid them in successive years).
I also don't understand how any owner can kick in their own money to pay salaries, which folks keep saying about Cohen (this makes no sense to me - does this actually happen? - owner's purchase organizations but they don't fund them out of pocket, they spend the money the organization makes to pay salaries, yes?).
So, there is a lot of money the Red Sox can spend, but there is some limit out there. What's that limit? And there's an amount that still allows them to build a sustain a team around Soto and an amount that begins to compromise that, in relationship to that limit.
Can they give a 700 Million dollar contract to Soto and still get a FA starting pitcher, another reliever, a solid RHH bat, a trade for another arm? Maybe they can. If so, I'm unbothered by the 700 million. OTOH, if that 700 million is going to make them a top heavy roster with a big star at the top, but lots of holes underneath him they can't address with money, then, no, maybe a line is being crossed with Soto now, and they should step back.
But it does seem they are sincere.