So this old man, who was obviously already searched because he was in custody inside the jail, had the potential to end their life at that moment?  I find that incredibly hard to believe. There is no testimony that he injured anyone, that he was armed, that he did anything other than disobey an order. 

Additionally, I was a cop for 12 years.  I absolutely understand how it works in the real world of policing (see Ferguson, MO) but I am also not naive enough to just blindly support the cops in any and all cases.  

While it certainly was "within their rights" as you say to make him turn over his shoes, disobeying that particular order was hardly worth his life.  There is a HUGE difference between lethal force being necessary and being justified.  In this particular situation it doesn't appear that either was the case.  

It does not take a genius to see that if they truly felt they had done nothing wrong there would have been no reason to make the Taser 'disappear'.