I've got exactly the same situaton now with a specification.
Someone has criticised a product specified claiming it to be unsuitable and unproven, but without offering anything they deem suitable to use in it's place. We know why, it's so they can then moan about any alternative we come up with, and they don't want to take responsibility for anything they might suggest to use.
The actual product is used up and down the country by thousands of companies and individuals and is well certified and up to any standard. But is unaware of it or the benefits of it's use. Closed mind syndrome.