Slut for Spinners
They seem temporary to me, since they appear to be fastened with a clamp ring of sorts around the columns rather than being welded to them. Besides, they're so long and slender they're there to take up tension forces, which usually is taken care of through other arrangements. I mean, if cross ties like that were necessary to make the great big hall stand up properly, you'd see them in a lot more places, and this is the first time I've seen anything like it spanned across the hall in that weird way.
You beat me to it - that interface at the top of the pillar suggests they're temporary until the structure is closer to completion.