For homeowner use, I'd do this. And I agree totally on osha regs. No modifications to cords.There's no way I'd use that on SO, and even less chance I'd use it on SJ.
For a jobsite, OSHA only allows unmodified factory made extension cords. No replacement ends, no tape, no splices, no repairs. Nothing.
For my own purposes, I'd take the two cut ends, add a plug and connector, and plug them together. Done.
This splice kit may be acceptable for UF, when something is buried AND not moving, but it's a recipe for failure on a flexible cord.