Package Management: some extras not listed, why?

A question regarding MODX Package Management and search :

Some packages don't appear (e.g. "mdetect" http://modx.com/extras/package/mdetect)
Is it a bug? Or is there any particular reason?
Does it mean something regarding extra stability/security/official approval?

That's because author set that it's not supported for 2.3. So you'll able to see those only in 2.2 installs.

Ryan also said on the last MODXpo that there are some bugs, causing some extras missing in the Package Browser.
So sometimes an email is required to be visible again.