While I do think “illusionary” is a bit too strongly worded, I do agree that it could be worthwhile to have a cryptographer researching Grin related topics.
Out of the things you mentioned, i think that finding a way to reduce the input and output linkability is the most pressing.
Since we obviously don’t have the budget to spin up a whole team of cryptographers, maybe we could find a way to structure it as a (post-doctora)l research grant in collaboration with a cryptography department at a university? This would allow for some senior supervision and give the person an environment to bounce ideas off of and keep up to date with related research. Just a thought, not sure if it’s a good one. It would make matters a bit more complicated for us and would maybe also be a too long of a commitment, since postdocs are usually at least a year long. And we might exclude some potential candidates who aren’t interested in doing it in this way. I also don’t know if any university would be interested in that kind of thing in the first place.