The game makes it pretty clear that the Radar Jammers are only vulnerable to snipers. But the game lies and tries really hard to hide this. Once its eye is open ANYTHING can damage it. The only problem is opening its eye. You need to look at the Radar Jammer with the Sniper zoomed in at most two times to have it open its eyes. Once to get it to turn to you, and another to get it to fully open its eyes instead of squinting. To prevent the squinting you need to make sure you zoomed in with the sniper and looking at it when it starts opening its eye. Otherwise, if squinting, you can't damage it and you are wasting time. (I know Radar Jammers can look and attack you even without needed a Sniper Rifle but that isn't consistent and I don't know what causes it)
For any% speedruns this could help because snipers restrict all of your movement and being able to switch out the sniper and killing it with a different weapon could save some time. However this doesn't really work because of two things. Like I said before, to have it not squint you already need to be looking at it with a sniper rifle as it opens its eyes. Meaning that you're already looking at it with a sniper rifle meaning that shooting it doesn't take that much time even though you are delaying the time it takes to put the sniper away and being able to move again. The second reason is that nothing else can kill it in one shot. The Gatling Gun shoots fast enough with enough damage that you could strafe under a Radar Jammer while shooting it to save time. However, the weapon is very far out of the way, having the homing launcher (and possible other weapons) means extra weapon switches are required to get to it, its spray is really big meaning that it'll miss a lot of shots which is a big deal since the eye isn't open for too long, and you may not be able to walk diagonally when shooting it which is the fastest form of movement. So for any% speedruns, I don't see it being viable without further refinements.
I overlooked something though. Each hit to the Radar Jammer, lethal or not, with increase your hit and combo counter by 1. Meaning that using the machine gun on one cycle of the Radar Jammer opening its eyes could allow for an additional 15 points to the combo meter. The Radar Jammers have 1200 health (USA version at least) and the blaster does 20 damage while the machine gun does 15. Meaning that on 1 Radar Jammer we could get a 60 combo with the blaster, and an 80 combo with the machine gun. Assuming only the Blaster is used on all 12 Radar Jammers on gold difficulty, that's a 720 combo only from radar Jammers. This means a score of 9999 is theoretically possible. Although it will take a while. The video I have linked below is me getting a 60 combo with the blaster from 1 Radar Jammer in about a minute and a half.
Since we can farm points from one enemy, does that affect 100% speedruns? Not really. The requirement for gold in that mission is rather loose and literally skipping the first phase of the mission still makes it rather easy to get gold. The Japanese release has a 300 score increase (equivalent to 100 hit increase) so it might be helpful there if the machine gun is used on Radar Jammers, although more testing would have to be done before definitively saying anything.
Video of 60 combo with 1 Radar Jammer (I used single stick controls btw):
