The International Paralympic Committee at first did not ban Russian or Belarusian athletes[0], but required them to enter without any national symbols. Which was how Russian athletes completed in the Winter Olympics. After enough threats of protests and boycotts that would have interfered with the games, it was decided to keep those country's athletes out.

Honestly, I'm not surprised. Though they were going to march under a neutral flag, they'd have still been emissaries of their governments. That's what the Olympics and Paralympics are for. Plus, the IPC's decision was probably easier because of repeated incidents of Russian athletes doping, which is why they were already under a neutral flag.

[0] https://abcnews.go.com/Sports/wireStory/russian-athletes-par...