Ya, the bolster will work for level 55s as well, if they are under geared. Could you post the stats on what you are seeing on PTS for your guy wearing legacy gear (or send the information to CommunitySupport@swtor.com, subject: ATTN Rob Hinkle, if you don't want to dirty up the thread). It certainly is the intention that your 55 wearing level 35 gear should get bolstered back up. To give everyone an idea (and BIG caveat here, this number is still in flux), but currently I would expect the new 55 bolster to be getting people into gear right around (statistically) non-augmented EWH.
Level 55 players are being bolstered? This sounds a little crazy to me. I always thought of the bolster system as something to compensate for players of different levels being placed together in matches so that queues could pop faster, and that bolster was not meant to replace gear for players that are of even level.
I think Bolster should not be a factor at all in the 55 bracket. That is why recruit gear was made so easy to obtain. A game needs to feel grounded by reality, even if that reality is entirely virtual and fictional. A "magical" feeling system that makes gear matter less is going to uproot me from that reality. For lower brackets, I totally understand. But, for 55, where everyone is going to be that level for a very long time, players will easily have the chance to make up for any poor gear and achieve a sense of progression and feel like their gear is improving. Using bolster at 55 to circumvent some of that feels wrong to the core.
Even if you give out completely free starting pvp gear, I like that solution more. Gear should determine how strong a characters stats are. The bolster system feels very black box and I don't trust it. Meanwhile, there are great systems in place to view and effect how my gear's stats add up and impact my character.