No, actually what is astonishing is your trying to show how an ERV ends up in the 'right place' in two species while using an ERV that does not link humans and chimps as an example to demonstrate it.
You need to keep up with your own argument. You originally brought up the ptERV sequence as evidence against common ancestry as it was an ERV found in disparate old world (specifically African) monkeys and apes but not humans. If ptERV was transmitted vertically transmitted to these species through inheritance it would completely contradict our understanding of the relationships between primate species, including ourselves. But of course if they were transmitted they would be found in the same places of the genomes of all those species i.e. the sequences would be orthologous as Taq has repeatedly pointed out. Instead the ptErv sequences are inserted randomly inserted, as expected if these were separate infection events after the species had separated, so the sequences were NOT spread through inheritance. This is why ptERV is not used for evidence of common ancestry, because it did not originate in a common ancestor.
Now ptERV is only one example of an ERV sequence. Many other ERVs do exist which can be used for evidence of common ancestry because they have been inherited from a common ancestor. We know this because the insertion points are shared across species. Your argument for this has been that separate infection events in different species have inserted in exactly the same position. But here ptERV can be used as an example of what to expect if your conjecture was true, but the pattern from infection as seen in ptERV is different from the pattern seen in inheritance. It also stands to reason that species with greater sequence divergence between species will also affect retroviral insertion sites. Of course Taq has also posted that excellent article on HIV insertions which shows the relative randomness in insertions.
And just as an aside, I had a quick look over the link to the guinea pig article and could find no comparison to a human ERV, orthologous or otherwise. It is recommended that you read the links you are citing to make sure it says what you think it says, otherwise people will be more skeptical of other evidence you post.
As for the source of seven shared ERVs between humans and chimps, the link only leads to a deleted blog post so can't confirm the veracity. It could be referring to ERVs only shared by chimps and humans but not any other apes, so occurred after the human/chimp common ancestor split off from other ape species.