Unfortunately I haven't been able to follow this season as much as I'd like to, due to work. But as far as I've understood, Anne just pressed her face against Markus' manhood. The HMs, who weren't at the party weren't allowed to react to the party in any way. Apparently Markus did laugh at the time, when Anne pulled his pants down and so forth. Which would also be reacting to the situation. He could've chosen to take a step back just as well. Also, apparently, Markus eventually told the situation didn't bother him.
Anne has a snowball's chance in Hell to win anyway, or even being in the final 4. Juridically what she did was sexual harrassment, I suppose.