According to the FM 3067 the Scorpions had only begun to introduce Protomechs to their touman at that point. The first deployemnt was with Chi Galaxy as a test and they were more focusing on using their new Undine battle armor at that point. And well we all know what happened after 3067 so my best guess would be limited deployment but stopped due to the necessities of the war and later relocation
Spot on, timeline fits perfectly
Plus it never made any sense for Scorpions to be using Protos in the first place
Protomechs are rationalized by writters as being cheap (lol) solution for a clan which is running out of resources
Scorpions made their entire living by extracting and processing abundant resources of their two resource rich planets
To say nothing of the fact that they always had decent amount of second line units and healthy recruitment pool for them
Only lore accurate reason for wasting time with Protos was FOMO, they have been late to Omnimech game before and had problems catching up so once new cool looking winderwaffle started getting hyped up they played it safe and got onto it but even then it was a second fiddle to more important projects like Undine
In the end the new wunderwaffle turned out to be a boondoggle so come first big budget overhaul (post exodus) they were discontinued
To say nothing of the mountain of freshly built vehicles, military mech and billions of newly available freeborns to cherry pick crews from once Imperio got off the ground
But that Triton protomech blueprints could be a good trade item for Hell's Horses, trading it for something Scorpions could actually use like Elemental III, Notos or Eurus would be a smart play