Well growing from seed starting in July in the Northern Hemisphere- it's moot.
If that seed came from mexi brick weed, it's NEVER going to finish before frost if you live up north.
Be more concerned about disturbing the roots on the tomato plant, which IS going to bear fruit.
If it's a tiny seedling, you can scoop it out and put it elsewhere but be careful n ot to break the roots when you do that.
Just don't screw up the tomato plant.