Yes Sony updates the PS3 but that doesn't change how you code it for really all Sony updates do is make the menu a little neater and all that nothing really code changing.
Also how can you blame Sony more than Beth the only thing Sony does with Beths games is make sure it dosen't blow up thier console that's it and Beth said before Skyrim came out that the PS3 got alot of attention and is working just as well as the Xbox and PC this trun out to be a lie they didn't do anything of the sort if they cared aout it's ps3 users then then would have held it back and told us stright that they ran into problems and are trying there best to fix them.
Support for the PS3 has stopped go to the PS3 forum it's a ghost town Gstaff didn't post a dawngurad update for the PS3 on the PS3 forum and even the mods have stopped coming in, way stop support a system you care about.
This DG problem is also a lie cause am stuck into my belief that they never intended to give the PS3 Skyrim DLC from the beggening and are just making it look they tryed so we wont be to harsh on them when they come out and say "your not getting it". (I would add a sorry but not once has Beth said sorry to the PS3 users for the problems they face with Skyrim or the delay for DG or the mistreatment of us PS3 users)
Tbh, even a simple change to the looks can totally remake the coding mainly because sometimes, they need to change, or remake, the coding in order to have the new updates. This happens a lot in many different things, like games and computers.. Heck, a good example would be Minecraft. Every time MC has an update, no matter how small, the coding changes a little (or a lot) which means the modders have to learn the updated coding in order to update their own mods.
So I still believe Sony prolly did something to their PS3s in order to make it hard to code for. Also, from what I've seen.. Bethesda does seem to care and you gotta remember, they are a company working for profits. They need to make money in order to continue their work and that can be a problem.. If it is taking long to translate Dawnguard then they prolly need to do some other things in order to bring in the money.. Other things like Hearthfire. Small, quick, and easy to make and can bring in a huge amount of money.. (Gotta remember.. 5$ per person and there are prolly over a million of Skyrim fans wanting it). And working on other things will slow down the process. This type of work isn't cheap and easy.. Also, they prolly hadn't post any info, or really done anything in the forums, cause they are prolly busy..Trying to get it finished and working.
So.. I still blame Sony for making it hard but at the same time, I'm surprised Bethesda hadn't figured it out yet and released Dawnguard for the PS3.. So I do blame Bethesda as well.