Wow... that's not entirely correct. Early bowmen rush can easily kill an opponent who wasn't clever enough to settle on a hill and build walls (and even then it's not certain thanks to Bab's buffed up Archers) - this may not happen on Deity, but still gives you a good start. Being ahead on the tech curve means you can crank out better units. In addition to that, leading in tech means you can build any wonder sooner than the others - you can still get a bonus to wonder building with policies, marble and pantheon.
You just gotta try it
It is a misconception that Babylon is all science. It is science that helps the other aspects of the game, should you decide to use them.
EDIT: here's two warmonger Babylon tactics to try:
1. Up to King: crank out bowmen, tech to Philosophy and build NC for tech boost, and then go down to the military side of the tech tree where all the units are. You will be able to wage war, get Crossbowmen fast, and upgrade to Rifles before the others thanks to NC. It is wicked fighting the AI's stupid swordsmen with riflemen already.
2. Up to Immortal: turtle in the early game with Bowmen, tech to Education, build some tech to give yourself plenty BPT and then go to the lower part of the tech tree. You will gain ground quickly and start cranking out gunpowder units in no time.
As far as policies are concerned, you only need to decide when do you want to wage the war. Do you want to tech up first or just try doing it right away? Babylon always gets to Rifles and Cannons first if played properly. If you want to do it right away, just play like Egypt's chariot rush and start with the enemy cities on flat ground while teching up in the meantime, and upgrade as necessary. You can easily employ the Rationalism jump for late warfare or a Liberty-Honor opening for some early wargames.
EDIT 2: Deity warfares are difficult, cause the AI gets a lot of stuff cheated in, BUT... as soon as you manage to get an AI opponent scared of your military, they will simply give you almost all of their gold and luxuries. When that happens, you just gained the upper hand. Now upgrade everything, buy buildings for more BPT and keep going. I had a game where Austria bought me off the war with 12k gold. Suffice it to say that in just one turn, my GPT, BPT and Military might skyrocketed