Not sure why it doesn't work, so can't answer that. I however did make this cfg based on yours and the stock squad decoupler / heatshield configs as examples. Seems to work fine with the minimal testing I did before posting it
@PART[HeatShield*]
{
MODULE
{
name = ModuleDecouple
ejectionForce = 100
isOmniDecoupler = false
menuName=Decouple Heat Shield
stagingEnabled = true
stagingEnableText = HS Decouple Not Staged
stagingDisableText = HS Decouple Staged
}
}