Yes, I too would question what application it is that asks to disable your AV and what is so suspicious that it warrants disabling your AV.
I can't recall the last time I disabled avast to install another program, so I would want to know why they feel it necessary, when this is the very time that you need your protection enabled. So it would be very much the exception than the rule to have to disable your AV to install a program and there would have to be a damn good reason.