In no way, shape, or form would the Boston Celtics fanbase ever consider rooting for the New York Knicks. They'd rather go through a voluntary lobotomy than do that. The only exception would be if the Knicks' success factored well into the Celtics' offseason plans, and this time, it would.
Whenever a team succeeds enough to find themselves very much in the thick of the title race, they don't make changes they don't feel are necessary. New York is one round away from making the NBA Finals, which could be far enough to convince them that they're fine where they are now, which could also mean they wouldn't interfere with the Celtics' plans to pursue Giannis Antetokounmpo.
As painful as it was to see them easily take out the Philadelphia 76ers in an easy sweep, that was further confirmation that Boston needs to make some changes. If they can keep the good times rolling against Cleveland, it will also signal to the Celtics that there's a high bar to clear next season.
Hence, it should further incentivize them to go after Giannis this offseason if they haven't already (remember that Brad Stevens is the NBA GM equivalent of a ninja). Better yet, with what the Bucks would demand, the Knicks would likely keep themselves out of the bidding war, as they may not see the price to get him as worth it.
Adding a Giannis type requires a hefty price
Antetokounmpo has been floated as a Celtics target for some time now, with many belieivng that Boston would be willing to dangle Jaylen Brown in a deal. That's a lot, but as long as Antetokounmpo promises to stay, it'd be easy to see Boston would flip that coin because they haven't come close to replicating the same success
If the Knicks make it to the finals, but don't quite get over that hump, sure they'd be into the idea of adding Antetokounmpo, but with what the Bucks would ask from them, they may not think potentially compromising a core as good they have been would be worth it.
Technically, that didn't faze Golden State circa 2016 when they added a player of a similar caliber to Antetokounmpo when they signed Kevin Durant, but they paid a pretty small price to make that work. It came at the cost of Harrison Barnes and Andrew Bogut. If that's all it takes to acquire someone like Giannis, everyone in the NBA would be in on something like this.
But it's not the same situation here. If New York goes far enough, they likely won't think a Giannis pursuit is necessary. For that reason, Boston should be ecstatic if their cross-state rivals make the NBA Finals.
For the record, no Celtics fans should be rooting for the Knicks' success. What they should be rooting for is as few Giannis suitors as possible this summer, so if the Knicks succeed in the ECF, that's exactly what will happen.
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