Yeah, the only way they could possibly adapt Lupinranger vs. Patranger would be if they completely reshot all morphed footage to have the two as always being equally-unified allies, have the Patrangers being squeaky clean role models with no hint of conflict whatsoever (to the point of even being more cheesy than MMPR season 1 and Samurai), and fully reinterpret the Lupinrangers not as thieves but as something like magicians or dancers or members of some other law-abiding top-hat-wearing profession... or maybe even just "superheroes" what with those big capes they have (and have them behave like Adam West Batman to really write home their law-abiding nature).
Having to do all that to make both as family-friendly as possible and to erase the original antagonistic relationship between the two (which would also mean nearly none of the original Sentai morphed footage would be usable) would likely be more trouble than it'd be worth to adapt LuPat at all.