Rehosting a GPL3 binary is not inherently illegal.
Inherently, no, but there are two arguments that have been raised which could be a differentiating factor here:
- The GPL grants no rights regarding the use of trademarks. In fact, the GPLv3 in particular explicitly states that the copyright holder may decline to "grant rights under trademark law for use of some tradenames, trademarks, or service marks". This is, for example, why sites providing WordPress (a GPL program) hosting as a service do not use the name "WordPress" in their name (trademarked), but rather the acronym "WP" (not trademarked). Similarly, Mozilla's Firefox (an open source program) has additional restrictions regarding the distribution of binaries bearing the Firefox trademark; this is why Debian's distribution of Firefox was named IceWeasel for many years, and why GNU calls their fork IceCat.
- Most of the GPL binaries being rehosted do not have the corresponding source code and build instructions attached, or even instructions on where to procure such source code (read section 6 of the GPLv3). Having it available would, naturally, allow a resolution to the first problem by removing trademarks from the binary.









