It’s just a type of injury. Injuries themselves don’t give you a right to sue, you have to be injured by someone else doing something wrong.
Can I sue for blindness? Yes, if someone caused my blindness in a way that they’d be liable for. Same with other injuries like broken bones or lost employment or embarrassment or paralysis.
So if someone drives drunk and hits you with their car, paralyzing you and causing loss of enjoyment of life, you can sue them and would have to prove liability (they caused your injury in a way that causes them to have to pay for it) and damages (the amount of money they owe you based on how injured you are). Something like loss of enjoyment of life would be part of the second part of the analysis.
Also, Merrick Garland is the head of the DOJ, and only the DOJ can prosecute contempt of Congress as a crime. So if Congress says that DOJ is acting in contempt of Congress, they’re asking DOJ to prosecute itself.