If you over oil the filter, yes, you will have to spray down the MAF. All the years I ran a K&N on my old 4Runner, I rarely cleaned the MAF and then only as a part of maintenance.

Other than that, use the oil to just barely wet the filter and you will be fine. Just as a note, I always used the oil in the squeeze bottle instead of the spray and just used enough to lay a light bead across the top of each pleat and let the clean gauze soak up the rest.