Why the rule or limitation of 50 Knots was placed upon the Crew is something else that needs to be re-thought.
How many millions of takeoffs have been done using the "Military" method by Pilots all around the Globe for at least the past Fifty Years that I know of....and that method is verboten by the CAA for some unfathomable reason plain escapes me.
Now if we could do that safely...routinely....repeatedly in helicopters with no Gucci Kit....why in the world could that "Tool" not be allowed in a Crew's Tool Box for the odd unusual instances such as befell the 139 Crew?
That assumes training, currency, and PROFICIENCY in the technique.