Yeah, this is an good idea (I’ve actually never realized that either) but no, the architects wouldn’t leave it alone just because it’s dangerous, they’ve captured an sea emperor leviathan, also, they have weapons that can destroy an entire solar system. I personally think the reapers may actually be newer creatures, and that’s way they are stronger against it, they’ve evolved to fight it, possibly containing small portions of enzyme 42

However another likely thing is that they have eaten peepers with the enzyme 42, combined with the fact they live in desolate areas.

@Player Number IDK Yeah I was thinking the same thing with the peepers, that the ones carrying the enzyme are their favorite snack, or specifically the one Maida killed ate enzyme 42 peepers the most. She also killed the thing 12 years before we met her so it could be possible that just maybe the adult emperor's enzyme was stronger back then and could keep infection away longer and the reaper meat maida was eating was rather potent with the stuff from eating peepers with more fresh enzymes. It would have been nice they had included something like that in one of her logs like "yeah i should be dead, did a scan of the reapers skull when I killed it, turns out some type of enzyme was in its bloodstream thanks to its diet when it was alive, me eating the meat passed some of the enzyme to me, kept me going till the symptoms finally let up, only took X amount of years."

Also, it may just be that she never even got kharaa, she did leave before the others got kharaa. Also, she is an mercenary so I wouldn’t be surprised if she sustained an injury and needed artificial replacements, which would also explain why it’d be easier for her to survive.

Edit: that may not explain it since Kharaa changes your DNA makeup and I don’t think she’s 100% robotic.

Also the thing with the reapers being new, that is a possibility, but the sea dragon was around during the time when the architects were on the planet and we know reapers were one of their prey, so it's a bit unlikely, it may be more likely the reapers evolved overtime though to be more aggressive to ward off predators

@Player Number IDK that is true that she may not have caught it but its ALL over the water and in the fish, the only way to not catch it is to not eat the fish and stay out of the water, she was the one going out for food, supplies, and fish samples for Bart to study, Bart didn't say maida was ill but he said "WE'RE sick" referring to all three of them.