Tightening torque on the four bolts is 22 ft.-lb, which is not much. However you might have trouble exerting sufficient force on your ratchet wrench if you can't position your upper body under the bracket (which implies that you have safely raised up the car a sufficient amount to get under it.) It wouldn't hurt to use threadlock but I would agree that is unnecessary since the original bolts do not have that.
The stock brace is steel, I believe the G7 is aluminum. There is a possibility of the bolt head working into the aluminum with use which would loosen the connection without the bolts turning. In that situation, you should not use thread locker until you are sure the joint isn't loosening from part deformation. So, install the part and torque it, mark the bolt position with a scribe mark or paint, then after some period of time, like 1000 miles go back and look for turning and check the torque by simply applying the installation torque again. If the fastener doesn't then, then run it a longer period of time, like 4,000 miles and repeat the visual inspection and torquing. If it doesn't move then, you are probably OK. Either leave it as is or remove it and re-install with thread locker if that makes you feel better. If it does turn as indicated by the marks or if it turns when applying torque, then you have a loosening joint. Whether the bolt rotated or the joint deformed with no rotation will tell you whether thread locker will help or not. In eather cas, re-apply torque and recheck in another thousand miles. Sometimes bolted joints seat-in and stop wearing. That isn't something you would do every time you assemble something, but for an unknown bolted connection, like an aftermarket aluminum piece replacing a factory steel piece, it's the right thing to do. Don't fall into the trap of believing thread locker always keeps a joint tight, it just stops the fastener from turning and won't prevent loosening because of a poorly designed joint that deforms or wears.