Honestly its rude to be invited by a country to meet their president who decided to respond to your criticisms of their administration only to not show up and go meet the opposition.
Being invided and then no showing shows complete disregard to basic diplomatic Etiquette since it was a mission to show solidarity against the embargo
Bonus socdems being cringe part 4.5: about another member that didnt show up to the presidential meeting
Show
Deeply unserious people
She may do good work elsewhere. She may have some valid criticisms (I cannot speak to this as I have not evaluated them).
However, when you're sent as a delegate of an ostensibly Socialist organization to one of very few actually existing Socialist countries and you get the immense privelege and oppurtunity to meet with the President of the country and First Secretary of the Communist Party YOU MEET WITH THEM.
To do so otherwise - again as a delegate of a supposedly Socialist org trying to make international connections - is so far beyond a faux-paux I'm not sure what to call it.
It's called sabotage. She skipped out on the meeting to deal with people who participated in the abortive color revolution from a few years back. She's an op.