Do i need an Istio sideload for this use case

I have 3 pods in a cluster - 2 of which have istio with valid gateways(an ingress and mesh) and one headless pod with no istio installed at all ( just a pod inside the cluster ).

The pod with no istio can talk to other services inside the cluster but requests from this pod dont seem to hit the istio virtual service therefore the routing rules get ignored.

eg

  1. DeploymentB can talk to DeploymentA - passing in header eg curl -H ‘deployment:blue’ http://deploymentA and as expected 100% traffic gets send to DeploymentA-Blue

  2. DeploymentB can talk to DeploymentA - passing in header eg curl -H ‘deployment:green’ http://deploymentA and as expected 100% traffic gets send to DeploymentA-Green

  3. But… Headless-Pod attempting to hit DeploymentA-Blue or DeploymentA-Green via use of headers - successfully hits DeploymentA but is load balanced 50/50…
    The virtual service is totally ignored from a pod thats not got istio sideloaded - is this expected behaviour… ???

*) Note that all ingress from outside the cluster works exactly as expected

DeploymentA-BluePod:: istio-sideloaded, gateway and vservice (matching on deployment blue exact)
DeploymentA-GreenPod:::: istio-sideloaded, gateway and vservice (matching on deployment green exact)

DeploymentB-BluePod:: istio-sideloaded, gateway and vservice (matching on deployment blue exact)
DeploymentB-GreenPod:::: istio-sideloaded, gateway and vservice (matching on deployment green exact)

Headless-Pod:: no istio - just calls DeploymentA blue via a header- but when i call deploymentA im loadbalanced 50/50 my routing rules in the deploymentA virtual svc are ignored