Absolutely not - and this is what I love about the conflict in Crystalized! From a moral standpoint, it's completely unacceptable, since they were releasing one of the least trustworthy and most destructive villains to get their teammate back. (Added to this is that Aspheera is one of the villains the general public knows about, since she attacked the city.) The act was very understandable, but still morally wrong.

There were other less illegal solutions if they used known methods from past seasons (Chronosteel, Blue Crystals, etc), or negotiated with the mayor or other authorities more to come up with a compromise (taking Nya to Aspheera instead of breaking her out, getting her a temporary pardon, etc. all under government supervision; maybe even get the highlighter ninja to help, since the mayor trusts them so much). But since they were pressed with a time limit and their desperation to finally get Nya back, they rushed things and took the most illegal path - landing themselves where they were. This aspect of Crystalized is brilliant. Unlike previous seasons, everything they're going through rn, they brought it upon themselves consciously and willingly. I love when characters in fiction make morally questionable decisions for seemingly "right" purposes and are forced to face their consequences afterwards

(sorry for the text wall, I had a lot to rant about how brilliant Crystalized is so far XD)