Seems like it would cause the same issue with the WD40 getting into BB. You don't want the WD40 to kill what grease is on the bearings in the BB now. WD40 probably wouldn't do you much good anyways, as it evaporates pretty quickly. It really isn't that difficult to remove the BB and if you don't want to do it yourself, I'm sure a bike shop would remove it, let you take it home and clean/prep it and then put it back on for a minimal fee.