- historically interesting
- can gaze in wonder
- can study it
- can port it to linux or windows (theoretically)
- can consider to contribute
- contributing to non Open Source projects is mostly wasted (even documentation or user to user help)
- if you like Open Source it's nice to show some support by releasing own software also as Open Source
- anyone who wants to redistribute it (for example the FreeDOS project could like to) can grab the binary / source and put it into their own releases without fighting with licence issues (important imho)
- no disadvantage?