Thanks all of you for your answers. I'll suggest FE Hoppy's wording to my chief.
I can see where the problem comes from. Try to follow as it's subtle.
We can see the word disengage as the action to switch it off. So you have to disengage the autopilot before reaching a certain altitude -> the "at or above" comes from that.
We can also see "disengaged" as the state of the autopilot. It's either on or off. Engaged or disengaged.
For example: at 92ft, the autopilot must be off -> it's disengaged.
So, the at or below is also correct!
Now, having the two sentences in the same paragraph is confusing.
I was told it comes from boeing and I did a little research. For sure I found it! The exact same two sentences in a document from boeing...
I'll have to check on a more official source but
this seems to come from them Page 22 Or L.10.10
Now I don't know how our OM passed the regulators but those two phrases passed the FAA ;-)
Now I don't know what to think anymore...