It doesn't say specify stock weapons though, it says "replace all
weapons", not just the ones they start with.
Never disputed that it doesn't replace the SB, just pointed out that "replace Storm Bolter with..." suggests that you need a Storm Bolter in the first place to be using that list, even if it says later on that you keep it .
I do see what you mean though, not saying it's ABSOLUTELY false so much as just dubious. I guess I never really thought of it before this discussion because I just assumed that "replaces all weapons" meant that you don't get to have anything else. Might ask about this on the other 40k forum I frequent and see what they say (since that's where I first "confirmed" this idea).
And yeah, that model costs more than my Scout Squad (4 Bolters + Heavy Bolter with Hellfire), but would probably kick their ass I suspect.
EDIT: Made that topic
and it seems the consensus is that you can't have a CML on top of a Hammernator according to RAW. But again I'm sure that if you clear it with your opponents all will be well!