I will not comment much on ruling on the legality of this equipment because case is very simple: illegal. But there is the other side of the coin. Broken plank caused irreparable damage to the class. I do not remember when a similar case of intentional violation of class rules was discussed recently. If someone commercially supplies equipment to the class he should take responsibility for it. If I understand correctly the end user stated precisely who supplied this gear. And if supplier commercially supplies these products he takes full responsibility. It does not matter who was involved in the build process. Subcontractor is nothing new.
In attached pictures you can see a vaneer. I guess used to confuse anyone willing to inspect the plank from outside pretending the plank is solid wood.
If supplier is confirmed I would expect our fellow TC member to resign from TC. It is hard to accept having him in the body that guards official specification of DN class.
The other topic is shall we recommend to a measurer to perform destructive measurement of DN equipment by allowing him to drill 5 mm hole? It would have zero to marginal impact on questioned gears. I think this situation may be a good reason at least to think about it as obvously fair play and trust have gone away.