"I hear Nebraska's nice."
From the moment Rick carried his injured son to the farm, Hershel has done nothing but good for Rick's group. He provided food, shelter, and saved Carl's life. In exchange for his generosity, Otis was killed, and Shane's loose cannon behaviour left Hershel and his family devastated. As if things could not get any worse, a walker popped back up to attack Beth, and Shane proved himself to be the world's least tactful human being alive, by getting mad at Hershel. Shane getting slapped at this moment was much deserved.
Very much aware of the consequences of Hershel losing it, Rick did the best possible thing by tracking Hershel into the town bar. With the emotions and loss too much to bare, Hershel relapsed into drinking his hopelessness away. When Rick's words alone were not enough to persuade Hershel, things got worse as two thugs walked into the bar, demanding to seek refuge on the farm. This scene showed Rick's loyalty, calmness, precision decision making, and complete intolerance for any possible further harm to come to Hershel's family. It is a good contrast to Shane's recklessness, and lack of regard for others. Expect tension between Shane and Rick to rise in the upcoming episodes.