This ... makes a lot of sense. One of the Siblings was supposed to be sleeping, per the Stormfather. The tower would have been abandoned by the time of the Recreance, when there was only one Bondsmith.
There are two major potential problems. First, it is implied there were multiple Bondsmiths *after* the founding of the Knights Radiant, but before the tower was constructed. (Can anyone chime in with a WoB on how long this period was?) Second, the Tower is a constructed entity, which may result in a high order spren (like the oathgate spren), but seems unlikely for such a godlike spren at the same level as the Stormfather.
Thoughts? Either way, I look forward to seeing Dalinar supercharge that tower!