Bulk minor-edits (tag changes, spelling errors etc) are usually discouraged and would likely be detected if made by lower-rep users because each edit has to be approved and large bulk edits are likely to be unapproved (depending on the impact such action would to the site). Such edits are discouraged because of the issue you have identified.
However, higher reputation users earn the privilege to not have to have their edits approved. This is because it is expected that by the time they have earned such a right they will have been active on the site for quite a while and would have picked up the nuances and best practices in that time so would know when it is or is not appropriate to make edits.
These edits were done during the weekend, a notoriously quiet period on the site (and on most stack exchange sites as well) so should such bulk edits be made this is the time they should be done. Higher reputation users would likely be aware of the quiet periods so would be trusted to only do such activity during these periods. Yes, it does mess with the front-page, but that's not the only page on the site where questions are viewed - the Questions page itself lists questions in newest order by default, so the front-screen only shows current activity.
Occasional general maintenance carried out at the weekend when the site is quiet isn't necessarily a bad thing, I'd be concerned if it was happening frequently or during the week but as it was quiet and not much was going on it's not really a problem (in my opinion) for this to occur every so often. In fact there are other suggestions for maintenance to do over the weekend, such as I suggested in an older meta post myself.