That really does look like a poor design. As MOB said, they've cored out the whole center of the threaded portion of the bolt for the placement of the magnet. It looks doomed to fail. I would think any FEA (finite element analysis) would have predicted that.
heheheheh
FEA....in this case gold plug uses that term in a different genre "Financial Extraction of Assets"
I see this all the time, all the folks, well, a HUGE portion anyways, of marketers of FARKLES that span a broad application spectrum, seldom analyze the aspects of each individual app...case in point here...while some drain bolts could be bored that dep, to house the SAME magnet they decided to use in all thier plugs, this application has issues due to the fact they compromised 80% of the gripping thread.
Now on to the torque issue...while some may think some egghead just copies this stuff from a chart, and applies it to every fastener accross the board, in a product, it is seldom so.
I'm sure great thought WAS put into the torque spec for the drainbolts on the C14, by test and evaluation of the prudent forces it takes to effect a proper seal using the factory installed bolt, and crush washer. Problem is that it doesn't apply to someones cobbldicked aftermarket part. There is a "Semper Fi" that must be applied, and adhered to, things like this are a blind Robin and will always occurr, because people just don't think about them well...
I'm willing to bet that plug would have ended up the same way by anyone saying they don't need-no-steeeenkeeeeng torque wrench for a drain bolt, simply becaus the 25nm (approx 20lb./ft) that was applied, is exactly the equivalent to what most people DO crank on that bolt using a socket and wratchet, they just don't realize it.... tighten a couple hundred thousand bolts, various sizes, using the Gudentight hand method, and then go and verify what you really tightened them to, you will find you many times actually exceded the rating, and most of the time are right about spot on.....using a hand wrench while laying on a floor upside down grunting, often results in using an effort much higher than most people realize.
Most people easily apply 20 lb/ft on a bolt using a 3/8" drive wratchet wrench without realizing it. Just sayin'.... toss in a 12" long breaker bar with that same socket on it, and see just how much torque you really applied....you'll be surpised to find you may have actually doubled it.... invest in a cheapo Crapsman 3/8" beam torque wrench, or similar, and walk around checking the bolts you hand tightened by trying to loosen them....the readings will likely surprise you.
I do have issues with the torque they printed for the oil filter install though....that was definatly a stupid mistake......I hope they revise the books someday.