Hi @GuiB, thank you for your reply, I used the second way as the workaround, I wrote a script to intercept "CMD+Q" and then forward to a complex combination which applied to Alfred.
I understand where are you coming from, the reason why I insist on "CMD+Q" as the shortcut is that I was constantly pressing on "CMD+Q" incidentally which caused my work lost for many times, then I realized I must mute this shortcut to save my life, unfortunately, there isn't a way to mute but remap as other purposes, then I replaced to spotlight's shortcut just like my "CMD + W" to my email client, because this two combinations are so easy to press with just two fingers from one hand.
I saw some other applications are able to override the native "CMD + Q" as the shortcut, I don't very understand why Alfred has to set this restriction rather let user to choose from their preference, I can't image an impact if override the native "CMD + Q" from Alfred's point of view for now.