The difference is that before the election, Lenin Moreno was seen as the successor of Rafael Correa (unlike the Trump and Obama situation). Correa's grant of asylum to Assange was seen as a political/ideological stand, and his successor was expected to continue it. When Moreno got elected he reverted enough of Correa's policies that the latter considers him a traitor [1]. That was unexpected.
> "“The greatest traitor in Ecuadorian and Latin American history, Lenin Moreno, allowed the British police to enter our embassy in London to arrest Assange,” Mr. Correa tweeted. “Moreno is a corrupt man, but what he has done is a crime that humanity will never forget.”
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[1] https://www.washingtontimes.com/news/2019/apr/11/rafael-corr...
> "“The greatest traitor in Ecuadorian and Latin American history, Lenin Moreno, allowed the British police to enter our embassy in London to arrest Assange,” Mr. Correa tweeted. “Moreno is a corrupt man, but what he has done is a crime that humanity will never forget.”