The FSF and SFLC have as much authority to sue people for infringing the kernel's copyright as I have: absolutely none. Only the copyright holders can do that.

The FSF and SFLC have as much authority to sue people for infringing the kernel's copyright as I have: absolutely none. Only the copyright holders can do that. Likewise, I can't sue people for trespassing on my neighbor's property. In the US, (1) you can't let an issue get bigger simply so you can claim more damages the way SCO tried; and (2) when there's a specific statute of limitations -- like there is with copyright -- courts are less likely to say somebody delayed filing suit for too long, unless they made statements about trying to make a record to qualify for more damages, the way SCO did. In the US, it used to be possible to lose copyright if you failed to enforce it, but that hasn't been the case for decades.