Hill has been a career backup, but is well respected in league circles. The 34-year old has started a total of 26 games in his NFL career, all between 2007 and 2010, and has a career passer rating of 85.9 (11th highest among qualifying active players). He has only thrown 16 passes in the last three seasons though, including none last year.
Walder doesn't exactly seem to be committing himself to the Jets having any high level of interest, so this may just be one of several backups in respect of whom the Jets have put out some feelers. If he was to sign for the Jets, he'd be a good fit for their system and presumably willing to accept a backup role. After all, who wouldn't want to be "the most popular guy in town"?