You are missing the letter of the law

It does not explicitly say anything about resignations. It references the deputy director who shall A) be appointed by the director; and B) serve as acting director in the absence or unavailability of the director.

The reading is vague but it appears to imply a temporary absence not a resignation. This will be argued in court but it says nothing of resignations. The office of legal council's memo would be worth a read where they argue this exact viewpoint.

I dislike the replacement and believe it violates the spirit of having an independent regulatory agency if a political appointment can be made in the interim without advise and consent from Congress, but the Dodd Frank act should have been more explicit when it came to resignations.

An independent regulatory agency is already a weird enough setup being in the executive but not under the executive. If you don't spell it out then bring in the lawyers.

I see this one going Trump's way.