To note, this (or an import through Wikimedia) is the only legal way to do a Flickr import (as uploading a photo attaches a copyright notice and a license to the file), and issues of copyright are quite prevalently discussed throughout the site. Additionally, the import function from Flickr doesn’t include all photos of the taxon, so sometimes you may have to import by photo ID (the last part of a Flickr images’s URL). It also seems that they fail to import if they aren’t licensed as Creative Commons. This can also be done with photos on Wikimedia, though I’d also highly suggest vetting the ID prior to import. Both sites often have misidentified photos. EoL used to have this compatibility as well, but the import tool no longer works there.
Regrettably, as noted by others above, the only means of flagging multiple objects here would be to flag each photo individually (and thus remove the photo from public view). Currently, the only flag that affects all of a user’s content is flagging a user for spam (which is restricted to commercial spam and shouldn’t be used for copyright violations). Staff have been looking into some additional hide-from-public flags, so it may be worth requesting if a “flag-user for copyright infringement” would be a viable addition to curator tools for mass-infringement issues.
The following links detail the current stance from site admins, which also entail when suspension should be issued in association with copyright infringement. The notes under Community Guidelines seem to apply to a single photo.