I've reported it, and hope an exception is made in this case, because by selectively removing slides this user has gone out of their way to hide the source.
Nope, an exception won't be made. On this forum you won't get banned for images plagiarism no matter what you do. Hell, nowadays even c/p text won't get you banned, let alone this. Take for an example
this case that I reported in which member copy/pasted someone else's painting pretending its their own, even lying that he will put it up for sale, making some bs story etc. Result was a couple of negative tags and that's about it, he didn't get ban.
What you should do is simply report that post as a low value and that's all that you can do about it.
It is applicable for images, signatures, arts, Telegram announcement messages, signals, everything. If what you posted is not from your own, you must leave a source link. Whatever you post, leave a link to show it is not yours.
Find me a case where someone got banned for using an image without the source.