If they are in Public domain and if you did not sign agreement with BNP that you won't make them available to the third parties, then yes, you can upload them on the site.
Some records that are not in Public domain yet have no commercial interest. As a proof they never have been reissued on LP or CD, so we assume that they never will be reissued in the future by the copyright holders. However, they may have high cultural value, so they still can be upload them on the site for educational and preservation purposes (under Fair Use provision) , however in this case the download button should be disabled by the user.
I also must mention that russian-records.com only provides media, we do not check for copyright statuses and do not bear any responsibility for the content.