Why does the ClickOnce Deployment installer run th

问题:

Why does the ClickOnce Deployment installer run the application during installation?

Details:

For an XNA 4.0 application I am prototyping it runs once. If you have Avast! installed and with its Deep Screen feature enabled, it will run twice (Avast! kills it and re-runs it).

Note:

This is similar to, but not the same as, Install ClickOnce without running. Please see that question for a solution to make it stop running the application. The answer is right here, you must use MageUI.exe. Here, I am only interested in understanding why it runs the application. What am I misunderstanding?