Sharoon, I don't know what you mean by reading Milton Friedman's post: Friedman died in 2006, and if posted a blog on this topic I haven't heard of it.
More importantly, it's simply not true that "maximizing shareholder value in defense sector means lobbying for wars." I won't deny that lobbying can increase shareholder value (witness, for example, the effectiveness of Franklin Raines in lobbying the Clinton administration to relax constraints on Fannie Mae and Freddie Mac, which started the subprime mortgage crisis), but maximizing shareholder value goes far beyond lobbying: it means deploying capital in the most efficient ways--whether that is R&D investment, higher pay for certain categories of employees, lower pay for certain categories of employees, increasing the sales force, improving the budget process, paying dividends, or (yes) buying back shares.