Now see, this is a proper Malfoid. Whorecruxes should take notes. This is dignified and ladylike. This is how it should be. No pornography. This is a LADY. Gentlemen respect ladies. Not Whorecruxes. Also, that's a genuinely nice fit. Good drip as the kids say.
If the diary is so unassuming, why would Lucius need to be rid of it in the first place? It makes more sense for Malfoid to either just have it or happen across it. This isn't even a drastic rewrite, it actually just cuts out a couple of lines and Malfoid having the book slots in perfectly.
With the #malfoid saga, I've been thinking about Ginny's place in it. Yeah, she'd make a fun love rival, but really, I think she'd be best left written out. With Malfoid existing, it'd be entirely safe to do so.
Malfoid already *has* the diary, and it'd make sense for her to write in it, such as with her Potter frustrations. The only other thing Ginny does (that I remember) is cause some vague "Oh I can't date my mate's sister" drama, which is nonsense anyway and redundant now.
Malfoid falling prey to the book also gives Malfoid a natural means of building up more good relations with Harry since he saves her, and would make Lucius begin to think twice about his allegiance if it hurts his family.