New Grenada? So probably late 1840s early 1850s POD based on his presidency. At the time he was still a liberal who respected human rights, so it would be a decent sell to the liberal clique and the Rojo ranchers who wanted a state protector.
It could be a stable union via the same language and similar institutions, while shifting debt to the Colombian state. It does screw over his position ironically. The people benefiting the most are the Cibao merchants who now get a stronger currency to use that cant be as easily manipulated via mass printing. As well as being an important transit point for investors going south to the main land.
The Cibao wouldn't like the ultra centralism, so that might push for federalism earlier. More importantly, the political stability and more migration to the island would spur economic development.
Unfortunately this would really upset the Empire of Haiti under Faustin. So a Colombian Haitian war is in the cards. Dont know how that would impact the politics in Colombia.