Okay--a quick search for "reversal" and "thiocyanate" turned up scads of postings and articles on reversal processing.
The two-cent summary is this: an otherwise conventional developer (D-19, for example) is modified with thiocyanate and/or thiosulfate as silver solvents to remove metallic silver and prevent fogging of the highlights. After development, a bleach step removes all metallic silver, and either chemical or light fogging makes the remaining silver halide developable. Any conventional developer, or a toner, is used to reduce the halide to metal (this is done to completion, since the image tonality is controlled in the first developer) and the result is clear highlights and black shadows: a positive.
If this were placed on a black background, the image would be hard to see; it sounds as if Rockland is counting on a thin surface image to be underlain by essentially unaffected (opaque whitish) emulsion. If there is no separate bleach step, then the silver solvent in the developer must be doing this job, but I can't figure out how the shadow areas get reduced to black. It all sounds more like a parlor trick than a viable photographic process.
A conventional (develop, bleach, expose, redevelop) reversal process using _white_ painted tin seems like it would work for "pseudo-tintypes". Everything after the first developer can be done in daylight, which might lend an element of showmanship to the process. Watching the positive image appear after the bleach step is really neat; I remember making black and white slides this way as a kid. And it is faster than doing two complete develop-fix-wash-dry cycles to make a printed positive.