I think it depends on your situation. Is taking the risk of not coming back or delaying your return is worth visiting Nepal. If you have to go...you have to go and you should take the chance else try to avoid it. The are many cases where people returned without any problem and i know few who were returned from port of entry despite of their valid visa and valid I-20 and they were returning from Nepal after a semeter break. So, overall...immigration of US is fked up so enter at your own risk.