No you don't. nobody ever needed to open a 3 post gauge to disable the mechanical limiter. A heck of a lot folks have done more harm than good by attempting to open a gauge.
The truth is, No matter where a electrical component is located, if the current path is broken, it cant function. Interrupt positive, interrupt ground, same result.
Lift a 3 post gauge from the panel and you'll find its mounting much different from typical 2 post gauges. There's a metal to metal connection on the back of a 3 post gauge that provides ground to/for a internal limiter. 2 post gauges have a single current path through the sender to ground. They are isolated from ground in the inst' panel mounting. So... Isolate that 3 post gauge from ground and that limiter is disabled, totally irrelevant. If the sender path through the other 2 posts is good ( this gauge measures 20 ohms ) the gauge will function just like any 2 post gauge.
Apparently you do have both standard and rally panels on hand so you could dig a little and figure this to be correct/true for yourself. You too might suspect that RTE never had a complete rally panel and a workbench. I assume they had a gauge alone and snapped a pic or 2 of what they thought was the necessary procedure.
The fact is, IF when bending the little thingy you should break the windings insulation shorting it to the bi-metal beam its wound on and didn't isolate that short from ground, this would function ( conduct current ) much like another, and defective, gauge attached to theirs or any secondary regulator installed. In effect, what you did was open one connection/current path and create another. So why bother opening the gauge when all you really need to do is isolate the gauge housing from ground in the first place?
The villain that desired the shroud of darkness didn't go into the switch to disable the light. He simply unscrewed the bulb a turn or two. Same principle.
I realized I couldn't undo this mess that had been created on the internet here but also realized at this point the creator(s) of this mess cant undo it either so... Good luck either way you go.