Well, since I'm apparently not going to get an answer tonight, let me put up what I'm looking at for others to digest:
Here is the official AAU results for the 1988 Junior Olympics Wrestling competition (all 3 styles, Sombo is the 3rd style).
As you will see, there are results for each place from 1st through 5th (fewer in less populated divisions). In 1988, the only 16 year old recorded to have won a silver medal was Scott Sylvester at 112lbs; all other divisions were uncontested. For the 1989 games, in the 17-18 year old division, John Coyle is the only player recorded to have won silver in Sombo (he won at 165).
Now I do not conclude from this that Mr Everidge did not win his silver medal as he claims, but there is certainly no basis for that claim in the official records of the Amateur Athletic Union. If this is an oversight, there will likely be photos, videos, hardcopy certificates, news clippings, etc. I would encourage coach Everidge to post the evidence supporting his claim, as it would definitely be needed to verify.
Again, it's not that it's been proven he didn't win his silver, it's simply that the AAU has no record that it ever happened, despite keeping sufficiently good records to note the silver medal victories of Mr Sylvester and Mr Coyle.