It's one of two things for me.

Either option a)
It's all about luck in Tans mindset.

Try Morison - He might have a bit of luck. Fell out with him, so appointed Hudson. Wait and see what happens. Might be lucky.
Holds on with Hudson, luck might change, so doesn't get possible replacements lined up.
Whitehead is caretaker - Might be lucky with him, let's wait and see. No point getting a shortlist yet, might be lucky

option b)

They do have a list of targets and none of them want the job.

I think it's a mixture of the two