This has only to do with labor laws and how contractors can be reclassified as regular employees under certain circumstances. For example, an employee cannot "quit" and then come back right away as a contractor to make more money. The IRS does not like this, because most of the time it is done by employees with extraordinarily long commutes or other ways to take huge deductions from their gross.
It also prevents companies firing employees only to hire them back as contractors to avoid paying benefits and FICA taxes.
Microsoft is only making sure they do not run afoul of labor laws. Because, you know, in its zeal to "protect" workers, the government would be all too happy to fine Microsoft millions of dollars and then not give a dime of the fine money to affected workers.