They're saying that without any hard evidence or proof.
All the various posts over at XDA indicate that this IS a hardware issue (the bootloader Youtube video kinda shows this). Lots of hardware issues can be fixed by using software workarounds. This is what I think Google is doing with this "software fix".
Just because they said they can fix it by using a software patch, doesn't mean it's not a hardware fault, which seems to be what Clove have gone to assume.
I have trouble believing it is a hardware issue, the only way I can think of why the volume control can be affected by RF is that the RF is coupling onto the volume control line and the modulated RF is then causing the signal to bang high then low.
If that is the case the the control line has to be long enough for an 800MHz signal to couple to it and if it could then theres nothing stopping an 1800MHz signal coupling to it.
Luckily I am on Orange so I havent had any problems with my phone and am really liking it.