The idea of not putting guns on your space ship in order to look peaceful should get you chewed out by the Gunnery Chief from Mass Effect 2. Any space ship capable of moving at any significant fraction of the speed of light (or worse, FTL) can deploy a Kinetic Energy Weapon that will devastate a planet or similar fairly stationary body. Strap a rock to the outside of the Tempest, fly at a planet, release the rock, destroy a continent.
Not having any weapons systems on your space ship means you don't have any kind of point defense either, which includes deflecting or destroying objects that your "shields" can't handle.
The best excuse I've seen by NOT-Bioware writers was to use the First Contact War as the excuse for not having any guns. Where that war started because the Human and Turian ships shot at each other over mistaken identities. So the idea would be to take the guns away so the AI side doesn't even have that option... which again, makes no sense as there are better ways to handle that. Such as locking out or unloading the guns until certain conditions are met, like being shot at first or detecting an object on a collision course that can't be avoided without additional "point defense" deflection.
Many aspects of the science side of Mass Effect: Andromeda fiction falls super flat. For example the Nexus should have been setting up a rotating habitat out of an asteroid(s) or similar body. I'd actually do at least one for each species. They have the Mass Effect fields for gravity manipulation to do the job fairly quickly. Doing so as an initial base would have solved so many of their start-up problems, like lack of space for hydroponics. Even with all the damage done by the Scourge. A self-sufficient orbital habitat will invariably be your first step in colonizing a new star system. In the course of a year they could have had a habitat up and running, instead of everyone freaking out and shooting each other in a riot. If you have the technology of the Mass Effect folks, you do not need a "golden world" to survive and colonize. Most of your material/resource mining is going come from asteroids and gas giants anyways.