According to ${WRKSRC}/README only commercial redistribution is prohibited which is what NO_CDROM is for. Also, we have LICENSE framework nowadays for more granular permissions.
The LinuxSampler library (liblinuxsampler) and its applications are distributed under the terms of the GNU General Public License (see COPYING file), but with the EXCEPTION that they may NOT be used in COMMERCIAL software or hardware products without prior written authorization by the authors.