I am just thinking that to laicize or excommunicate a bishop is a horse of a different color, than doing likewise to a simple priest.
Strickland is walking a fine line right now, between accusing the pope of manifest heresy and declaring the office vacant, and pulling his punches short of that. Either one of those would indeed be Rubicons to cross, and Vigano has crossed both of those Rubicons.
Yeah, I don't think he'd laicize him, but then nothing Bergoglio does surprises me anymore. If Strickland makes any more public accusations of heresy, he MIGHT get the letter to appear in Rome on charges of schism like +Vigano did. Bergoglio weighs whether by excommunicating him they'd just give him more publicity and get more Conciliar conservatives in an uproar against him and tempted to follow +Vigano into sedevacantism.
I think that the "last straw" against +Vigano was when +Vigano accused him of having predated upon a young man some years ago. Bergoglio knew that the secular media, unaware of the theological finer points of Catholicism, would construe any action he took against +Vigano as retribution for +Vigano having blown the whistle on the McCarrick crimes, so it took something like to get him so irritated that he took the chance of it backfiring on him.
Now, perhaps the reason they didn't "laicize" +Vigano is because ... how do you really laicize a schismatic anyway? It would be like if a Catholic Pope laicized the Orthodox ... they're already suspended and prohibited from offering Mass, etc., by virtue of being in schism and/or excommunciated. Laicization is actually typically done as a "mercy" to the offender, whereby they'd be freed up to marry, etc. ... but for someone who's already excommunicated/suspended, it doesn't really mean much. It's not like they can actually REMOVE Holy Orders from the individual, where if he decided to ignore it and offer Mass anyway, it would be invalid, since he's now a layman.