Possibly they delayed because:
1. They wanted to wait... and wait... and wait... to give Bekele as much time after London to make it less likely that he'd still be injured or on the verge of re-injury
2. They had no confidence in Tokyo going ahead in the summer and didn't know if they needed to bother
3. They felt Tokyo was going to happen but be postponed, meaning potentially there'd be races beforehand which would make selection easy and save them the trouble
4. They wanted to hold it in Ethiopia and enjoy a nationalistic atmosphere, but Covid along with civil unrest meant they had no idea if or when this would be possible but still clung to the idea it might be so kicked it down the road
5. They are quite incompetent
None of these are mutually exclusive... but probably a combo of #4 and at least one other