I've come to think of that as part of his charm - and you want to root for him on the rare occasions he does well. It can't all be down to the AI's inability to use his UA since, as above, that's not especially powerful. And the AI can be a military threat with plenty of civs that have no inherent combat advantage, such as Egypt and Russia.
I cannot root for him.
When I was Washington and I smashed his cities and capitals with riflemen, he sat down in his remaining four cities and seethed for revenge. When neighboring early Renaissance Spain was overrun by Alexander's cross-continental WW2 invasion (and me last-minute intervention to divide Spain because
holy poo poo Alexander on my continent), he planned. When the Iroquois and Rome fell to Alexander's atomics, and I turned America into a police state, he glared his glinty Viking eyes, and made deals with Alexander the Son of the Gods.
I know, I watched them. Watched his WW2 infantry on amphibious exercises in Alexander's Spain, them going in and out of the water near my borders, or the occasional show of force near American-occupied Copenhagen.
Then Alexander won his diplomatic victory, I discovered I had no uraniums and two closest sources of it were south in a Greek-allied CS, and I hammered that CS for its uranium...
Denouncements from him, from Rome, from my old friend Alexander of the Gods.
Then I took another City-State to fully cement my southern security. I was planning to cement it further in the west and the north, Oh the North where the Norsemen and Grecians are, my first two submarines were making their way to the Pacific where Grecian carriers with atomics were spotted in previous friendship cruises.
Then Alexander of Macedonia declared war.
Then Harald Bluetooth declared Ragnarok, for time has come to liberate Copenhagen from the hated backwardly backwards foe of yonder, and I quit the game because holy poo poo I had no Manhattan and Alex had 12 and more and atomics on carriers and so many more city-state allies on my continent.
So I tell this story to warn ya'll with the fires of a defeated president. Beware the hospitality of the Viking, for he just wants to stab you in the back for all time.