That may be true of Soliloquy, but I'm not sure it's the case that lattice problems were originally researched as an antidote to QC. Lattice theory has applicability to cryptography in general, so it's natural that people explored its suitability as a crypto primitive.

I don't think it's reasonable to draw the conclusion from this paper that "cryptographers set out to foil QC and in this case failed". One derivative scheme in a broad class of lattice crypto designs fell, that's all.

Lattice crypto has very strong post-quantum crypto marketing, because of NTRU.