remove and then add wpautop

Well, removing autop filter from the_content filter tag makes no sense here, because you never apply the_content filters in your code…

Let’s take a look at the source code of the_content() function:

function the_content( $more_link_text = null, $strip_teaser = false) {
        $content = get_the_content( $more_link_text, $strip_teaser );
        $content = apply_filters( 'the_content', $content );
        $content = str_replace( ']]>', ']]>', $content );
        echo $content;
}

As you can see, it applies the_content filter to the result of get_the_content() function.

So how your function should look like?

function yb_link_post() {
    $link_post_title="<strong class="headline"><a href="" . get_permalink() . '" title="' . esc_attr(get_the_title()) . '">' . get_the_title() . '</a></strong>';
    $link_post_content = $link_post_title . ' — ' . get_the_content();

  // you don't have to remove autop filter if you want to run it anyway... and content is already modified, so it will be `autop`ed correctly.
    $content = apply_filters('the_content', $link_post_content);
    $content = str_replace( ']]>', ']]&gt;', $content );
    echo $content;
}

PS. You shouldn’t use <b> – use <strong> instead. Also you should escape eveything correctly (i.e. if you print get_the_title() as html attribute, you should run esc_attr on it).