I think it's actually much stronger to protest when the club is doing well on the pitch. It's not like the Glazers have changed their approach to United from one year to the next since Ferguson left. So if you weren't happy with them when things were going poorly, and you're happy now things are looking up, then your issue is not actually with them, but with the people running the football side of the club back in the club's offices. I mean, it's not like the Glazers hired Ole, or bought Lukaku, or fired Mourinho too late, or bought Bruno, or whatever good and bad footballing decisions have been taken in recent years.
I anyway feel this has been conflated in a lot of the discussion. I would say that, if your issue is with football decisions, then the issue you want fixed are things like Woodward possibly not delegating enough of that, or a lack of DoF, or issues with the approach to scouting. in that case, these are interesting times, as Woodward is going away, the football structure has been revamped with a DoF in place, etc - and that may mean things really are looking positive long-term. (Or not, but it's wait and see right now.)
But if your issue is with the ownership structure, or the commodification of football and the club in particular, or with the overall financial planning - then the Glazers are the target and football results don't matter. It's obviously easier to motivate fans to act in dire times, but the statement is stronger now.