D&D is ultimately a set of rules to guide a group improv storytelling session. One of the first rules of improv is “yes and” so you go with it within the confines of the game rules as well as what people are comfortable with. This is where /u/[email protected]’s suggestion of “Ranlar slowly rises from his wheelchair before collapsing under his own weight as his atrophied legs give out. Your party must now find a way to move him away from the orcs without using his newly healed legs, perhaps on a nearby chair with wheels.” Fits so well. It "yes and"s the spell while remaining true to the other player’s wishes.

The DMs job is to maintain the fun for the players, and if one player is ruining others fun they need to be spoken with and kicked out if they aren’t able to be a team player. Personally, I treat a NAT20 (and critical failures) as an opportunity to do something comical that helps advance the story and improve the lore, because that creates the moments you tell to others when sharing fun stories about D&D