Most people don't update their firmware unless there is something that they need that was fixed in a later release, so it makes sense that they will hold them to update them if it's a mandatory update.
That been said, people are assuming that's the case just because of some shipment delay, the thing is that we don't know.
As for downloading firmware and installing it yourself, Rigol is pretty good at that, you just have to ask them for it or wait for someone to post the new update in some forum. But unless you want to get burned, wait for others to comment on firmware update experiences before upgrading yours if you have no immediate need for whatever the new firmware addresses.
Case and point upgrading to a version that disables the bootloader with the potential to brick your equipment, I haven't updated min DS2000 for almost a year now and I see no need yet. Eventually I'll evaluate what updates and fixes they been addressed and pick the one with less problems.
A company could have hundreds of QA/QC employees and they might still miss something that hindsight 20/20 would be obvious to test for in the first case.
I mean, Rigol is only a 16 year old company, and for being that young they sure have the right processes in place IMHO, but you can't expect them to have the same level of process sophistication as the bigger players and even those bigger players miss on things often.
Sometimes fast reacting companies don't have stable products, as an example at work we had XP until windows 7 was stable enough and we skipped on vista all together. I will imagine that once windows 8 is stable enough for all our toolchains and requirements we will migrate to that, but it's not mature enough just yet. I like somethings they've done I will adapt to other things I don't like but I know we will eventually migrate unless is a flop like vista was, same with with windows ME.
The point is that running the latest release also means the less tested release.