No, this does not meet the goal. Creating a resource lock and assigning it to the subscription is not enough to ensure that when an NSG is created, it automatically blocks TCP port 8080 between the virtual networks. This is because a resource lock does not affect the configuration or functionality of a resource, but only prevents it from being deleted or modified1. A resource lock does not apply any security rules to an NSG or a virtual network.
To meet the goal, you need to create a custom policy definition that enforces a default security rule for NSGs. A policy definition is a set of rules and actions that Azure performs when evaluating your resources2. You can use a policy definition to specify the required properties and values for NSGs, such as the direction, protocol, source, destination, and port of the security rule. You can then assign the policy definition to the subscription scope, so that it applies to all the resource groups and virtual networks in the subscription.