A few things here: 

1-) We need to create tickets in http://tickets.opscode.com/secure/Dashboard.jspa describing what's the issue on these platforms so that they can get fixed.
2-) A comment here pointing to the issues that says once fixed this should be removed and tests should be enabled. 
3-) Don't know what platforms its checking in the File.exists? section. A new filter for it... 
4-) Less offensive name then :buggy_platforms :) Maybe :xxx_bug_platforms where xxx shortly describes the issue