Another reason why it is in the buyer's best interest to keep the sale confidential ... and require the seller to do so until the buyer wants to be introduced to the employees, which is typically just before the closing, maybe a day or two before.
Almost always the buyer is purchasing all of the assets out of the seller's corporation or LLC and setting up a new entity. So, in effect, all the employees are "fired" one minute and "re-hired" by the new owner the next minute. If employees have known about the sale in advance, the buyer has no idea if one or more has been looking for another job and might leave shortly after the closing. When it is presented to them as a fait accompli, they are far more likely to give the new owner a chance.
The new owner needs to treat the employees with respect and assure them that their jobs are secure, and
can also provide incentives, e.g., a bonus if they stay for six months or a year.