Microsoft recognizing the union instead of fighting tooth & nail to destroy it is genuinely novel behavior. They could refuse to recognize the union, or sue to invalidate the ballot, as many, many companies do:
"Activision Blizzard did not respond to workers’ request for recognition of a union formed by quality assurance testers at Raven Software" https://www.washingtonpost.com/video-games/2022/01/25/activi...
"The NLRB found Curaleaf violated federal labor law by refusing to recognize and bargain with workers there, but the company is appealing the decision. Curaleaf had initially challenged the result of the election, which the union won by one vote, but the labor board later ruled in UFCW’s favor." https://www.gmtoday.com/news/illinois/2022-saw-a-wave-of-new...
"The decision ordered Starbucks subsidiary Siren Retail Corp. to negotiate with the new union at its Seattle Roastery restaurant... The company contested the union's victory because the government held an election by mail ballot rather than an in-person election. Starbucks plans to appeal the ruling." https://www.shrm.org/resourcesandtools/legal-and-compliance/...
"Since the workers went public with their union and began to bargain, Trader Joe’s has cut hours of union employees under the guise of the "slow season," while at the same time hiring new workers and giving them full-time schedules." http://www.fightbacknews.org/2023/1/3/minneapolis-newly-orga...