There are numerous justifications for sealing in the first place. Minors, unindicted people, classified information, open investigations being the legitimate ones. Courts will allow sealing embarrassing material for their special customers, and will ALWAYS try to hide its own misconduct.
The Weiner case involves a minor, so evidence and motions that could identify the minor are sealed until somebody demands them, at which point the court goes through a review and makes a decision how to handle the demand. Redaction, let it fly (sometimes minors are treated as adults). The laptop contains classified info, we've been told that. But I see no reason THAT material should appear in THIS case, at all.
I don’t believe Weiner was ever indicted by a grand jury. Sealed indictments become public when an arrest is made.
This seems to be unsealing of some documents related to his guilty plea.