Read the bug report. The accessibility feature works. The submitter (who also happens to be the bug reporter) found a fairly minor subfeature (the ability for sticky key modifiers to act as lock keys) has been broken recently. I say fairly minor, because the only key this might be critical for in certain use cases is the Shift key, where a separate Caps Lock is already available.
The bug is asking for the wrong fix
Different modifiers have different combinatorial effects. Caps Lock is not necessarily Caps Lock, in other words. I know that most Linux people hate them because they are cheap, and you have to do a "disable secure boot" dance to install Linux on them, but ChromeBooks, in particular, lack a Caps Lock key. Caps Lock is achieved by hitting both shift keys simultaneously.
If that isn't convincing enough, consider Alt-Gr vs. Right-Alt behaviour on international keyboards that report a USB HID country code of 00h.
While I was working on ChromeOS at Google, there were a number of obvious usability issues for the OS, but the majority of them stemmed from the need to upstream support into Linux, and the difficulty of doing this without involving an Alan Cox, Ingo Molnar, or similar personage when you were dealing with things which crossed area boundaries. Input is one of these areas, and it was rather difficult and roundabout to get support for non-adjusted raw system time stamps in evdev inputs, even as a non-default option.
Exaggerating the issue by claiming it makes accessibility on Xorg unusable and bitching on slashdot because its been a whole 11 weeks since he found the problem and noone has released a fixed version yet is just grandstanding.
I agree the issue is exaggerated, but mostly because I disagree about where in the input stack usability issues should be addressed. The usability belongs in the input stack, as does the internationalization, below the point at which events are reported to the console, or to X (or Wayland or whatever display server is handling the apps and forwarding the input events).
It's pretty easy to see where this breaks down by enabling "programmer mode" (meaning: disabling "secure boot mode") on a ChromeBook, and enabling root or other console logins. It's easy to see the shift-shift (or Caps Lock, if you plug in a standard USB keyboard) and internationalized input don't work the same on the console as they do in the graphical environment.
In general, the input stack in Linux has a *lot* of problems. A fun experiment to try is plugging in 3 or 4 USB keyboards, and playing with the Caps Lock; the light goes on or off on whatever keyboard you're playing with it on, but the actual Caps Lock state depends on whether you've hit the Caps Lock key on an even or odd number of keyboards, and the keyboard Caps Lock lights very quickly become desynchronized from the actual Caps Lock state (i.e. turning Caps Lock on on keyboard A lights the light on A, and hitting it on B turns it on on B, rather than off on A, even though the state is that Caps Lock is no longer in effect).
Similar issues occur when using sticky modifiers for usability, and when moving between virtual consoles with various modifier/Caps Lock/etc. states in effect.
I understand the idea that you may wish to explicitly allocate resources in a multihead environment, but the input stack really doesn't do that very well, either - these modifiers should happen in the input stream above a stream join as a resource allocate by a virtual console or display server, and not in the display server or the underlying driver.
Windows doesn't support multihead well (at all, for multiple sessions, without something like Citrix intermediating the process), but it also doesn't screw up on where it put the internationalization translation tables and the dispatch routines and the usability.
PS: In case you care, AFAIK, there are zero vendors who put the correct internationalization keyboard code type in the USB capability report for keyboard HID devices like they are supposed to; in general, it's handled by using an internationalized version of Windows instead - in other words, the correlation between the keyboard on your laptop and the OS is done via a ROM/EAROM device capabilities region, even if the internal keyboard in your laptop is interfaced via USB.