Apparently they ended up having to do just that even after paying the ransom:
"The decryption software provided by the hacking group DarkSide, notes Bloomberg, was reportedly 'so slow' that Colonial Pipeline 'continued using its own backups to help restore the system.'"
I mean if you have backups then sure, don't pay. Every case won't be that simple. It also seems a bit odd that they'd pay if they truly had all the backups they needed.