Something funny is going on. On my iMac, running 10.12.6 (Sierra, with all security updates)‚ pressing Shift gives the choice of ~/Library but pressing Option does not. I don't know if this is relevant, but I have my preferences set to ALWAYS show ~/Library when I go into my User folder.
I just tested on my Mac running 10.13.3 beta and enabling the "always show ~Library" changes the effect of the various modifier keys when used with the "Go" menu.
- ~/Library is ALWAYS on the go menu regardless of modifier keys
- SHIFT — switches to wide menu display and changes "Enclosing folder" to "Select Startup disk on desktop"
- OPTION — changes the "Enclosing folder shortcut" from ⌘↑ to ⌥⌘↑ (I have no idea why)
- CONTROL — Same as Shift
- COMMAND - no effect