There's still the military aspect of it. Ethiopia wants to set up a navy, mere commercial port ain't going to cut it. It would jeopardize Djibouti's lucrative foreign base business. Giving a regional hegemon like Ethiopia a naval base would negatively impact the existing foreign bases in Djibouti. It also won't address the elephant in the room, Egypt's entry into the Somali arena.
Still, good move by Djibouti. They're doing everything in their power to disrupt Somaliland MoU with Ethiopia. This means they view us as a serious competition.