This is not correct. Sometimes inaction is much better than action. In the case of a corrupt government, inaction is always preferable.
The US constitution is built to create deadlock. See checks/balances. It is this deadlock that has lead to American prosperity. While it is unable to do good, it is also unable to do harm.
The question this essay asks is, how effective is it at those goals? Are there situations where it could all collapse? If yes, are there other systems which are less likely to collapse?
People who complain about "deadlock" are really complaining Congress isn't implementing their legal and budgetary priorities. But that isn't because there's something wrong; that's because not enough of their countrymen agree.
A perfect case in point, the patriot act and the department of homeland security. That represented action taken. Solutions developed. Where they the right actions and the right solutions? Not in the least. Would we be better off without them? Probably.
That is not the system we have: we have a fully-polarized system in which each major party's agenda consists primarily of ensuring that the maximum number of items from the other party's agenda to be enacted will be zero (I say "maximum", because rolling back or repealing any previously-enacted items is also an option). Since they're both quite good at the tactics, the result is inaction even in times when action is needed, to the detriment of the American people.