Starvation in Priority Thread Schedule by Setting

I'm trying to create some code that will simulate starvation of multiple threads based on priority scheduling (FIFO). The code below is supposed to set the program affinity to a single CPU so that no multi-threading can occur, then I spawn all the threads with different priorities and wait a sec to make sure they are all set up and in a waiting state after which I release the mutex and due to the FIFO scheduling policy the thread with the highest priority should be able to proceed and then run forever starving the other 2 threads. Here is my code...

#define _GNU_SOURCE
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <sched.h>
#include <unistd.h>

//global variables
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

void* tfun(void*n){
    struct sched_param param;
    int num_runs = 20;

    //set priority
    param.sched_priority = (int) n;
    sched_setscheduler(0, SCHED_FIFO, &param);

    pthread_mutex_lock(&mutex);
    pthread_cond_wait(&cond, &mutex);
    pthread_mutex_unlock(&mutex);

    while(num_runs) {
            printf("thread priority: %d\n", (int) n);
            //num_runs = num_runs -1;
    }

    return NULL;
}

int main(int argc, char* argv[])       
{
    pthread_t tid1, tid2, tid3;
    cpu_set_t cpus;

    CPU_ZERO(&cpus);
    CPU_SET(0, &cpus);
    sched_setaffinity(0, sizeof(cpu_set_t), &cpus);

    pthread_create(&tid1, NULL, tfun, (void *) 40);
    pthread_create(&tid2, NULL, tfun, (void *) 30);
    pthread_create(&tid3, NULL, tfun, (void *) 20);

    sleep(1);
    pthread_mutex_lock(&mutex);
    pthread_cond_broadcast(&cond);
    pthread_mutex_unlock(&mutex);

    pthread_join(tid1, NULL);
    pthread_join(tid2, NULL);
    pthread_join(tid3, NULL);

    return 0;
}

When I run it, instead of getting my expected behavior of "thread priority: 40" printed endlessly, it seems to cycle between all the different threads still and print them out as well.

I'm not sure if there is anything wrong with my code, but I am using the WSL (Windows subsystem for linux) and I was wondering if that was maybe causing my issue as the affinity setting is a linux thing that may not translate correctly in it?

build command
$gcc -o main main.c -pthread -std=gnu99 -D_GNU_SOURCE
run command (sudo because changing priorities)
$sudo ./main