I envy you going to Esxence!
Interesting questions/speculations about Tonatto. It does seem personal, if no one had anything nice to say about her and someone went so far as to call her "a horrible woman." Does seem odd.
Her absence at Esxence, on the other hand, is probably her choice. I assume that anyone legitimately in the industry is eligible to register and participate. That's how most trade shows work, it's not usually by invitation. So it's usually a business decision -- what does it cost in registration fees, display materials, staffing, travel, and so on; versus what do you stand to gain from the new exposure and contacts. If the company has few new products, or none, there may be less reason to participate.