Agreed. Copyleft Free software with an option to purchase a non-copyleft license exception is strictly better than proprietary software, which in many cases is the only realistic alternative. If there's something immoral about selling these exceptions then it's also immoral to release software under permissive Free licenses, which is a very unusual belief.

RMS discusses this here:

https://www.gnu.org/philosophy/selling-exceptions.html

"I consider selling exceptions an acceptable thing for a company to do, and I will suggest it where appropriate as a way to get programs freed."