Go the other direction of the orbit!
I posted after I fixed the problem, but at the time all I was thinking was "My tug pilots must have heart eyes and be knee deep in drool. . . " since I didn't notice until a few months after I gave them their orders.
On another note, I started from scratch a new game, literally from scratch as I made a new system and empire and everything. Tried to make them robots that are fueled by minute amounts of airborne methane and freeze every colonizable planet they see, but that didn't work out as well as I'd hoped. Good news is though, there's almost never a system I can't colonize with minimal effort since they can survive in next to no atmosphere with mega cold temperatures basically, which maxes getting on asteroids and comets without underground infrastructure super easy.
The main point is that before I got past my own system, as I only explored that first jump from the home system, I get aliens popping up at the 21 year mark. My record for aliens is well over 150 years, and I'm the one to find them. So worth it to have one pre-made at the game's start. . .