It's not like it happens every time, but happening even just once when you don't expect it is enough to make a note of it. I've had it happen a couple of times
Make note of, sure. Why not? But it's hardly a design flaw, at least not any more than any safety which can be inadvertently engaged or disengaged with inattentive manipulation. In general, the degree of ease with which it can be engaged is proportionate to the opposite. And on that note, I've had holsters both engage and disengage frame mounted safeties. I consider it a holster problem, not a firearm design issue. But I did reduce the lever on my Witness compact 10mm for that reason, since it was carried IWB. Never had the slide mounted safeties on my CS45 or 4516 engaged by an IWB holster.
I also don't carry handguns with an empty chamber, so even if I did manage one day to accidentally decock and safety on chambering, it would be remedied before holstering to go about my business, making it a non-issue.
it seems to me that the pinch-grip slingshot, when performed quickly and instinctively angles the muzzle towards the strong side about as much as a properly executed overhand rack angles the gun towards the weak side.
I don't see any way a pinch grip can result in more than a few degrees deviation from straight ahead on the horizontal plane without deliberately (and awkwardly) making a point of it.
I've watched many people use, and many instructors teach, an overhand method that turns the muzzle perpendicular to down range (held in the way you would take down a glock), advocating the mechanical advantage of pushing your arms toward each other. This can put it in line with your weak hand forearm, and anyone standing on your weak side.
Not for me.
Would do it almost every time unless I purposely altered the way I racked it. And I wouldn't always do it because it was different from how I racked other guns
If one way works and another doesn't, and you refuse to adapt, that's a you problem, not a design problem. Somehow many are able to effectively manipulate weapons with a different manual of arms. I don't forget that Colt cylinder releases go back instead of forward like a Smith, or that my FAL charging handle is further forward on the left, different from the AR, AK and many others. I've never attempted to lift the bolt handle on a Schmidt-Rubin. And I've not had a problem forgetting where a safety is, which way it goes, or how to avoid unintentionally engaging/disengaging when manipulating the weapon. These are overt and tactile things, not like an unusual button layout on a keyboard.