How to alter default ajax_view default ScrollTop?
As @Clive mentioned it is because your JS order load is wrong(your JS loaded before than views JS)
I suggest you instead add JS in hook_init put it in hook_form_alter or in hook_page_preprocess 

drupal_add_js( drupal_get_path('theme', 'MYTHEME').'/assets/js/MYSCRIPT.js',array(
            'type' =&gt; 'file',
            'scope' =&gt; 'footer',
            'weight' =&gt; 100,
        )
);