The answer quoted above said they needed to spend time to "untangle it of some commercial code that was used at some point." That just strikes me as a bizarre problem for Canonical to have even had.

Only if your focus is open source. UbuntuOne was conceived of as a service, so to make the project go faster and solve problems commercial products were used. As you'd expect you then have to disentangle that code to release you code as open source - happens all the time in big proprietary code bases that are being open sourced.