Smithfield Foods is a multi-national food producer and packaging Corporation that sells much more than just pork. The range of subsidiaries for this company is stunning! America's food supply would be significantly compromised by the purchase of this company by a Chinese firm, and the consequences, in terms of food safety, future food costs, or what is simply "good for America", are difficult to see as anything other than potentially damaging.
The potential for historically lax standards from Chinese production facilities, combined with reduced inspection from USDA due to budgetary concerns, and the resultant health risks in the nations food supply are enough of a concern to warrant firm action. The possibility that other, more harmful actions could occur, make it absolutely necessary.