I am part of the Debian Med team and we'd like to package ViennaRNA to be part of Debian. We work to ease the distribution and use of bioinformatics software for end-users/researchers/....
Your license is non-free (that's fine to be packaged in Debian in
non-free section), but the license text does not explicitly allows
source redistribution (restriction on usage is explicite), only usage/modification.
If source redistribution is ok for you (keeping licence text for usage restrictions), would you mind updating your license text to add source code redistribution grant ?