Over my ~40 year career in Propulsion, there were a lot of "unintentional" engine shutdowns, for various causes. Switch confusion (actuating fuel switch instead of the EEC switch - resulting in the relocation of the EEC switches to the overhead), fuel configuration or fuel pump errors, even accidentally snagging the fuel switch with clothing while reaching for something else. I never heard of one related to a drink spill or other liquid contamination.
In short, this is a pretty serious miss by Airbus - something that should be designed for at a very basic level.
Something tells me the tone of this thread would be quite different if this had happened on a 787 instead of an A350...
For the reasons described above, this AD requires amendment of the AFM.
That'll almost certainly be an interim step to mitigate the problem, while Airbus comes up with a permanent solution that corrects the fundamental problem - which will then get it's own AD.