First, as to making a proposal in general ....
There is a place in the 'substantiation' part of the proposal where it is appropriate to post links to someone's product, links to forum discussions, etc. These are appropriate in demonstrating that there is an issue to resolve, a need for a change.
Of course, to do so you also must identify just exactly what it is that needs change or clarification.
Regarding the "Powerbridge" specifically, the code issue appears to hinge upon the use of this product as a substitute for the fixed wiring of a building.
One very real possibility is that the panel will see a need to clarify that such an arrange is indeed part of the fixed wiring or circuit extension - despite assertions that the use of an extension cord proves that it is not.
Another possibility is that the panel will itself assert that it is up to the manufacturer and NRTL to instruct users that the product is not intended for direct connection to house wiring, and requires other freestanding elements (such as a UPS) for compliant use. Not too likely; as we saw with 'power strips,' it is more likely that a product standard will be written that precludes such an arrangement, perhaps by requiring the use of non-NEMA plug patterns.
As with 'power strips,' the main source of opposition to this product will be that it makes it far too easy to introduce code violations, through the misuse of the product.
This is exactly the dilemma faced by folks who sell tear gas, lock picks, pornography, marijuana growing equipment, and drug paraphanalia: how do you market something that is so useful in breaking the law?
For that matter, this is the issue law enforcement confronts daily. Do you just 'happen' to have antifreeze, ammonia, and cold medicine - or are you setting up a drug lab?
A successful proposal will have to calm these concerns.
