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
There are specific reasons but don't forget that the people Trots fight with the most are always each other.
But basically they have different ideas about what direction to go in and how to "lead" "the movement". They're like little parties within a party but neither of those things is really a party at all. But seeking self-promotion and being more vanguardy than each other is part of it.