I would say it is more for perfectionist sake, rather than for reverse-engineering. It is quality control by Piotr.
When molding for silicone it is more like 'not capable' of remolding. Unlike acrylic ciem's, silicone is not a hollow cavity that you simply stick your drivers in; where you depend on the quality of the drivers and the hardwired crossover. With silicone all space is filled; there is a new dimension involved for design. You need to drill pathways and design for how the acoustics will bounce all sound. Other third-party remolders will simply not follow manufacturer's vision in the final sound-tweaking via acoustical design.
Plus premium manufacturers are always obsessive of their designs being taken to a tangent. Luxury European manufacturers limit the ability to mod their products by contract with their customers (any machine loses it's warranty, but people may be more empathetic to a car example where normally modding is expected i.e.
Ferrari's no-mod contract). This is could normal to Piotr, but a culture shock for the rest of the internet population.
tl;dr: CIEM designs have evolved to be more complicated than simply remolding.