Because a tornado's max winds are rated based on the max 3 second gust, and unless this tornado was moving >100 mph (which it wasn't), its size would expose at least certain structures to high winds (including the UK Grain Center) for a longer period than that.
Edit: maybe to say that point was nonsense was too harsh, because I do understand the angle (contrasting with something like the Jarrell tornado), but I think given that there have been a number of other fast-moving EF5 tornadoes and this one did produce a lot of higher end damage, it seems there was enough exposure for total destruction in many instances.