Severance Packages Under Fire

I read today about the severance packages that Amazon.com is offering to the ranks of its recently laid-off employees.

At first glance, the packages appear pretty good. Many folks are being offered two to three months pay, relocation assistance,and $500 IF they sign an agreement indicating that they will not speak to the media about Amazon.com.

Union-types contend that this is unfair and violates rights of free speech.

Several questions:
1) What can these people say or know about Amazon that is so critical?
2) Amazon's not forcing these people to sign off on the agreement, so how is this wrong?
3) Does this not beat the heck out of receiving no severance package at all?