Complex sentence: He specifically dislikes some provisions in the new license which prohibit the use of the software in digital rights management (although GPLv3 has no such prohibition) and it would also be impractical to obtain permission from all the copyright holders, who number in the thousands.
Split into simpler sentences: He specifically dislikes some provisions in the new license which prohibit the use of the software in digital rights management (although the provisions in question do not actually prohibit this activity). It would also be impractical to obtain permission from all the copyright holders, who number in the thousands.