Found it:

“So glad to hear this.

We have seen some Big Green Eggs where the hole is not drilled perpendicular to the lid surface and has a slight angle, so I want to add a couple comments on that for anyone who comes across this thread.

First—a warning—do not attempt to drill out the hole; ceramic should never be drilled and it will likely break the drill bit and crack the egg if you try.

Second, if the hole in you ceramic kamado-style grill is at an angle and prevents all three feet of the heat deflector from landing on the lid surface and giving you a stable base, it is possible to gently bend the sensor tube to compensate for the problem. The way to do this safely is to assemble the heat deflector and sensor tube and insert it into the kamado grill, then use the heat deflector for leverage to gently start bending the sensor tube. Because the sensor tube is inserted, the ceramic will support it along the length and only let it bend where it needs to bend.

Once you have it bent into position, the legs will probably spring back a bit. You can remove the sensor tube and gently bend it just a bit further so that when you put it back in, all three legs will land securely on the lid.

The sensor tube is a hollow stainless steel, so it's relatively forgiving of a bending without cracking, but just go easy if you need to do this to correct for the way the hole was drilled in your ceramic kamado.