Aws-cli: ec2 describe-route-tables with filter "Name=association.main,Values=false" not working as expected

I was hoping to use this filter in combination with "Name=vpc-id,Values=$VPC_ID" to get all route table while discarding the VPC's main route table, but this also filters out route tables with "Associations": [], where it should not.

Here is a example to illustrate the problem

$ aws ec2 describe-route-tables --filters "Name=vpc-id,Values=$VPC_ID" 
{
    "RouteTables": [
        {
            "RouteTableId": "rtb-186a857c",
            "PropagatingVgws": [],
            "Tags": [
                {
                    "Value": "dev-vpc-default-gw-routing-table",
                    "Key": "Name"
                }
            ],
            "Associations": [],
            "Routes": [
                {
                    "State": "active",
                    "DestinationCidrBlock": "10.0.0.0/16",
                    "GatewayId": "local",
                    "Origin": "CreateRouteTable"
                },
                {
                    "State": "blackhole",
                    "DestinationCidrBlock": "0.0.0.0/0",
                    "GatewayId": "igw-35fa8b50",
                    "Origin": "CreateRoute"
                }
            ],
            "VpcId": "vpc-09be846c"
        },
        {
            "RouteTableId": "rtb-096a856d",
            "PropagatingVgws": [],
            "Tags": [],
            "Associations": [
                {
                    "RouteTableId": "rtb-096a856d",
                    "RouteTableAssociationId": "rtbassoc-6469c600",
                    "Main": true
                }
            ],
            "Routes": [
                {
                    "State": "active",
                    "DestinationCidrBlock": "10.0.0.0/16",
                    "GatewayId": "local",
                    "Origin": "CreateRouteTable"
                }
            ],
            "VpcId": "vpc-09be846c"
        }
    ]
}

$ aws ec2 describe-route-tables --filters "Name=vpc-id,Values=$VPC_ID" "Name=association.main,Values=false"  
{
    "RouteTables": []
}