(oops I spelled revealed wrong in my previous typo/post.)
Here are some random thoughts of speculation unordered.
Besides pictures, reports from different news sources, witness statements that reported the tether wasn’t released, and that the driver thought that the towline was released, I am comfortable stating that not releasing the towline is part of the chain of things that could be involved in the crash at Jean Lake.
Not releasing could well be one chain link all by itself that caused the crash without any other links involved. At this point I’m not referring to weak-links but only a metaphoric chain of events that most often are involved with aircraft accidents.
Not knowing what type of release was being used will cause a multitude of possible scenarios to be considered.
Knowing what type was used would cut the possibilities considerably.
Can the Medical Examiner rule out heart attack, stroke, aneurism, conflict of prescription medications, diabetic or any other incapacitating event happening to the PIC before impact?
A disabling medical event as the root cause would shorten a lot of speculation.
If the PIC’s video camera is able to convince us that he was trying to control the emergence it would be safe to speculate that it was equipment malfunction possibly.
How close was the release activator to the (PIC)?
Would a lockout to either side place the passenger in the way of the release and out of reach of the PIC?
If the accident investigators at the crash scene can activate the release with no trouble at all at some point they should try activating it under various tensions up to breaking the weak-link. What tension does the weak-link break at?
Another possibility is that the weak-link due to a routing tangle never came under tension at all. Next try activating the release at increasing tensions until the towline breaks without a weak-link play. Will the release still function at these higher than normal tensions?
Will the release function when the towline is slack?
If the towline is trailing the PIC can the release activator still be reached?
If the release bridle has two leg (lines) and one leg broke would that place the release out of line and reach of the PIC?
If one leg of the release bridle separates from the harness and rather than slip free but have a wrap and capture could that place the release out of reach?
Enough speculation for now----