The repeater tax applies if over 3 of 4 seasons. Getting under for just one season does not change anything. I see no indication that BOS has a goal to get under the tax.
It doesn't change anything for this year, but it does change the 3 out of 4 timeframe and would allow the team to escape the tax in a future season.
Since the team is winning, I tend to agree with C21 that ownership will be less inclined to demand further cost-cutting.