They have no context assigned, therefore they show up in the "no context" list. They do only show up as Available if they have no further actions to be completed, which is your cue to either add some or complete the project (or drop it or put it on hold).
If you don't like seeing projects and action groups in your context lists, you can disable the behavior by unchecking "In Context Mode: [] Show Projects and Action Groups" in the Data Preferences in OmniFocus for Mac (the setting is synced).
If you only have the iOS app, turning off the option is a bit trickier. Open Safari on your iOS app and visit this URL (it may be necessary to copy and paste it):
omnifocus:///change-setting?ContextM...sParents=false
Code:
omnifocus:///change-setting?ContextModeShowsParents=false
(yes, there are supposed to be 3 '/' characters, not 2)