Article is wrong. Ecobee does have a disable standby screen option and the ability to set the brightness the same for active and inactive.
Disabling the standby screen is not the same as disabling the proximity sensor. I you disable the standby screen timeout then the Ecobee will not display the standby screen but it will still dim the screen brightness after some time. When the proximity sensor is activated again the standby screen brightness will get brighter. You do have the ability to set the screen brightness to the same level for both active and standby thereby negating the problem of causing this modulation on Shabbos. However, the downside to this approach is that besides having the screen brightness cranked up all the time, you also lose the outside weather station reporting you would normally have on the standby screen. If you however just put a piece of opaque tape on the proximity sensor the device will change to active mode when touched and will go back to standby after the set timeout.
I should have included your option in my article. I probably didn't think of it at the time because when I got my Ecobee I in general didn't like the idea the proximity sensor activating the screen every time I passed by even during the week. There is no way to disable the proximity sensor and have the functionality I described so I just covered it with a small piece of tape which is barely noticable.
Now that you have pointed this out I will update the article. Since these settings are adjustable with the API it would be possible to have the settings changed right before Shabbos and Yom Tov and changed right back afterward.