It is not immaterial who is producing the different editions; at the very least, it tells you to whom you should be directing your anger.

Blockbuster was almost certainly not doing any editing itself, simply for the cost of running a VHS/DVD production workshop at that scale. Doing its own editing without permission of the video owner would have been outright copyright infringement, and they would have had the pockets and visibility to be sued for doing so.

Another thing worth pointing out: rental editions are generally produced and released before retail editions. It's very possible that mistakes identified in a rental edition could have been rectified for the retail edition, and Blockbuster in particular is unlikely to have replaced its rental edition stock with retail edition stock if such changes were made. Just because a change exists doesn't mean that one copy was intentionally censored.