avast treatment

[superhacker]

i run a virus after disable avast then re enable it(trojan)
i start a memory scan avast detect the trojan process and ask me to take a choice i decide to delete file but when scan finish avast tell me to do a boot time scan i open  procexp manager and see the process of the virus so why avast dont try to kill the process of the trojan to prevent the next situation:
pc infected by a trojan i plug a memory stick trojan will try to put autorun.inf and its file and avast warn you about the virus and you choice to delete it but the trojan will try again to put the files and so...

[.: L' arc :.]

why avast dont try to kill the process of the trojan to prevent the next situation

 To prevent dreadful system instability when a false positive is detected.

 So to make it more vivid in thought, let's think of a situation wherein avast detect lsass.exe as a trojan which is actually not [an FP]. So let's say if avast terminates lsass.exe's process, there will be a sudden error or a restart.