This is the last official version of shorten, version 2.3a from 1999.
The LICENCE isn't FOSS compliant, sorry about that, it all started a long long time ago. If it helps, the company assigned the IP was never interested in exploiting it, went dormant in 2007 and ceased trading in 2016. The company that inherited the rights never had an interest and has been taken over several times since. There probably is a legal owner but they don't know it.