I see using it a currency backed by scientific work is already something that makes using it unique and can make people interested in accepting it and use it. I see that you don't view it the same way, but that's okay too
As well, here's one thing that may or may not usecase per se, but it is something a that's different from most cryptos in use of the coin itself. It's nice feature that only a one or maybe a handful other coins [1] called sidestaking. With it you can send any % of your staking rewards to other addresses in the coinbase transaction. So you could for instance use it to donate to BOINC projects that accept Gridcoin every time you stake (and people already do that). Or you could send it to a friend when you stake or anyone really. You can send to multiple addresses every time you stake with different % for each (up to 6 before it has to cycle through them on each stake) to. On the flip side, accepting Gridcoin means you can also accept sidestakes (at least for things like donations)
[1] Pinkcoin is the only other one I know of and could find (https://www.youtube.com/watch?v=HTuM69Lgd5o). Looking it up just brings me mostly to Gridcoin stuff