I understand he is referring specifically to a silicone layer CLD aluminium armtube. I would be wary of generalisations to other viscous layers, constraining layers, geometries etc.
Your original reference was to melamine foam for acoustical room absorption, where I can see that the open cell properties will be of use. Inside an armtube it is not so clear what effect it may have on structural resonances. I did see from the Korf blog, measurements of damping increasing the Q of structural resonances. In any event, melamine foam is cheap and readily available, so it will be added to my list of things to try. It seems like I will have to develope a test method for assessing the techniques. I intend to post the results. Don't expect anything too rigorous though.