Yes, read the last sentence of my comment. Updates might re enable it. If your battery runs out, the same happens.

I've removed the Siri button from the touchbar the day I got my MacBook, more than a year ago, and it never appeared again. Might be a problem on your system? Usually resetting the NVRAM/PRAM solves this kind of problems, but it's basically black magic.

Did you remove the Siri button from the touch bar, or disable Siri altogether? Maybe try doing both.

I removed it once. I may be mistaken here, but if I recall, removing it slightly shifted the layout of the other keys throwing off my muscle memory for the f keys.

I'm interested in a solution. I probably hit that key unintentionally 10 times a day.

Check out this post about customizing the touchbar that was on HN a little while ago: http://vas3k.com/blog/touchbar/

Perhaps you could replace the Siri button with a similar sized button if one is available, in order to keep the spacing. (I don't have a touchbar Macbook, so I don't really know what's available.)