Tor's license appears to be a standard 3-clause BSD license, which permissively grants virtually all copyright rights, with the requirement that redistribution includes attribution of the original authors and a copy of the license.
The other page you've linked to is entitled "Tor Trademark Frequently Asked Questions". The FAQ item you quote deals only with the question of when you may use the registered trademark name "Tor" in a software product. It does not address the rights to modify or distribute code from the Tor project, which is permitted at large by the permissive 3-clause BSD copyright license applied to the code.
To answer your question directly: yes, the copyright license permits you to release commercial and/or proprietary software based on Tor software, but the Tor Project's trademark policy will not allow you to use the identifier "Tor" in your software's name. In fact, they generally forbid any derivative software product to use the Tor trademark name or logo, commercial or otherwise. You may ask the Tor Project for a trademark licensing agreement to use the name in your software product.
Generally under trademark law, you may use the name "Tor" as an identifier in a description of your software's origins (e.g., "This software uses an onion model similar to the one used by Tor" or "This software is based on the Tor software project with the following specific improvements...") as long as your use is not confusing to consumers. It must be easy to understand that your project is not sanctioned or approved by the Tor Project, even though it uses code from Tor.
