A bit of a tip toe towards tapering?
Well, the Fed's portfolio is rather small so the amounts shouldn't really move credit markets whatsoever. As of last month, the Fed held roughly $5 billion in bonds and $8.6 billion worth of ETFs in this space, which isn't a whole lot at all if you think about the $1.4 trillion in corporate bonds sold this year so far.
As such, if you're going to just base it on flows, this isn't anything significant.
The move by the Fed to buy corporate bonds was more symbolic if anything else, so the unwinding could perhaps be taken in the same light.
Tapering is of course the thing that everybody will be watching for from the Fed ahead of Jackson Hole but this is perhaps the smallest (or "biggest" depending on how you look at it) that they may give up until then.
If anything, it just reaffirms that they are going to take things rather gradually and slow-paced so it isn't to say that tapering is a given over the next few months.