Well IANAL either, but I know there are a whole raft of rights associated with a work, and just because it's out there, doesn't mean it's public domain (which has a specific meaning). It is possible for a company to permit people get it from their website but not allow redistribution by other sites, or other means. It is all in the fine print.

It is possible that Broadcom hasn't thought hard about this (perhaps they are not as lawyer-obsessed over there), and simply put it out for all and sundry and don't really care that much, after all they just want to sell more hardware. But the redistributions rights may not have been established. and cannot be assumed.

Sometimes a workaround is to distribute a script that fetches the software from the official site. This was what was done with the Microsoft TT fonts, for example. But of course there is a Catch-22 in fetching from the net without a network driver.