garnishment/forced time off

What is the name of your state? MN

Can an employer legally force you to take 2 weeks off without pay if you were served with garnishment papers twice?

Many States have reg's which specifically prohibit the employer from taking adverse action against an employee due to garnishments. I don't know what MN reg's are on this. If nobody else here can tell you, then I suggest you call Minnesota's Department of Labor and inquire.

Processing garnishments is, quite frankly, a pain in the fanny for the employer but suspending you for two weeks thereby making it even more difficult for you to pay the debt seems like stupid move to me, regardless of whatever the law is.