I do think Mr. Gardiner counted on Mr. Bennet’s anger and indolence to keep him away from the wedding. That was necessary in part to shield Darcy’s participation but also because Lydia needed to be married before she returned to her family and home where gossip is running wild. I agree there is a plan to disassociate the Bennet family from the dubious ceremony but not that there is a plan to disassociate the family from the marriage. If the family wanted to be disassociated from the marriage then Lydia could have been married from the rooms in which Darcy found her, instead the Gardiner’s bring her to live at their home until the deed is done and Mr. Bennet could of continued to refuse to notice Lydia on her marriage but instead is persuaded to invite the pair for her good. Marrying Lydia from the Gardiner home and then allowing them to visit Longbourn publicly brings them into the family rather than distancing them from it IMO. ;D