Amazon is not supposed to fire workers for promoting unionization of the workforce. That is specifically illegal. However, Amazon knows it is almost impossible to reinstate these workers if Amazon refuses to let them back on the property. Amazon may have to compensate them financially for having illegally fired them. Amazon can afford it. However, the National Labor Relations Board does have the power to impose a union on Amazon if it finds during the course of it's investigation that Amazon has negatively interfered with the legal efforts to unionize the workplace. A pattern of Illegal terminations would also fall into that category. The NLRB can impose the union even if the majority of the workers are against it, if, in the NLRB's opinion, the majority of the workers would have voted for a union contract if Amazon had not been interfering with the effort illegally. This has happened many times in the past. Amazon will have already hired the very best people to keep the union out, and the union will also be bringing in their very best to organize the workforce. Both sides will know the entire history and the current status of the labor law that applies here. It's a high stakes game of chess they are playing now. Moves and countermoves are deliberate. NLRB serves as referee. Wallmart, for example, has been known to close locations rather than accept unionization imposed upon them by labor boards. They've done it more than once. If Amazon is forced to accept a union, they may also close down the operation. Amazon can hire another company to do the work for them, without the union. Amazon can still keep the internet front end, etc. This is all totally legal. The government, of course, can also retaliate. The government has the legal power to do anything it wants to a corporation. So it becomes a question of how many senators Amazon has to bribe. That's the American way.