Correct.
Default is impossible, given the revenues coming in.
Then there’s only symbolism in raising the debt limit.
Good move on the GOPs part. Makes them look flexible and willing to horsetrade (when they don’t really need to), further highlighting that it’s the Dems who are being intransigent. Plus it keeps the focus on the shutdown and Obamacare, preventing the Dems from distracting by crying out “defeult!”