I guess that I'm reading this differently than almost everyone else. I'm reading this as the IA has been doing the maintenance and annuals of this airplane. I'm guessing that there's an agreement or history that when the owner does maintenance, the IA will signoff said work after inspecting it (I had this arrangement with my old IA).
The IA sees what's going on but has no idea about the rules of this and figures it would be best to find out before the owner has spent time and money on the work. Finds out that it's not okay (whether it's accurate or not) and lets the owner know so they can stop before putting any more time into a project that the IA will not sign off.
Now the way I did with my old IA is BEFORE doing anything, I would talk to him about it. He would then advise me on any common pitfalls of the task, offer a special tool if one was necessary, and tell me to let him know when I was done so he could inspect and sign off the logbooks. One time I wanted to do something and he told me that I couldn't. Actually, he said I could, but he wouldn't signoff on it because it wasn't approved or legal.
But without hearing from the IA in this case, we'll never know for sure about the events or motivation. But that never stopped POA speculation, right?