If the sources produce significant sequences that match the original binary, that binary is probably infringing. The community gets around this by distributing binary patches instead.

In some cases the EULA is what gives you access to the original binary to begin with (often the case with digital marketplaces, but also true of some physical media after 2010 or so). These have little to do with copyright, but whether someone could access the binary on the first place. To the best of my knowledge this contract law has largely been considered valid, but I try to avoid working on things with EULAs, so haven’t looked into it in depth.