The TDI might be a stretch, not from blade length, but from its handle design. A Hideaway could work, and so could a Hartsook, fitting the sheath under a belt loop and running a cord around another loop. Hard for someone to feel threatened by a Hartsook, or you could look for a used Buck Smidgen, which is the same design in 420HC and without the black coating. If the Izula comes across as too large, I suspect the SPEW might as well. The Minimalist has a better sheath than blade, given CRKT's habit of cheaping out on steel and their proprietary Nev-R-Sharp heat treatment.
You could also try the AG Russell Woodswalker if they ever get them back in stock, or the Hunter's Scalpel. I've heard good things about the latter, and the Woodswalker is an excellent small utility blade. I just wish it had a more pronounced self-guard, which the Minimalist design absolutely gets right.
While it might be unpopular to say so, you could always get a BK11 or 14 and cut down the blade to make it more tool-like. You could then justifiably say you felt it looked too intimidating and you wanted a tool with a full-length handle rather than a weapon. It would look even less threatening if you cord-wrap the handle with bright colors.