Just for the development team, I followed up with the observer of the 2nd link, and asked if they had done something different to enter that inactive taxa.
They replied they just ‘typed it in’. Everywhere I tried to do just that, either when I hit enter the field blanked out or if I tried to save with that in there it blanked out the taxa box upon saving.
I dont know if there is another variant of ‘just typed it in’ I missed trying. The only obvious difference was the observer was on a Mac and I am on a Windows machine, so maybe some behaviour difference between how Chrome and Safari deal with lookahead typing ?