Great idea! Would it be worthwhile to create a bot that adds a message to these issues, including a request for help? That way, the original reporter will get a more substantial notification and call to action.
Something like, "Thank you for reporting this bug! We have noticed that this issue has been open for quite some time and want to make sure that this bug still exists in the current version of Astropy (v7.1 or whatever). If possible, please let us know if this problem still exists or if it has been resolved and this issue can be closed. Thanks for your help in improving Astropy!"
I don't know how hard it is to make a bot to do this, but it seems worthwhile.
Kelle