Handing Guatemala over to Mexico better served the Austrian Empire's long-term interests.
For a great power, Mexico's population was simply far too small—so small that the Mexican government had yet to complete its exploration of its own country.
Annexing Guatemala could increase Mexico's population while also putting some pressure on the British. Britain's colony of Honduras had always been left to fend for itself, yet it still brought in considerable returns every year.
This was mainly because its neighboring powers, France and Austria, were each preoccupied—one with suppressing internal unrest, the other with developing land. Neither had either the motivation or the strength to threaten the British colony.
But a Mexico that had annexed Guatemala would be entirely different. Mexico proper would then directly border Honduras and could easily mass troops for a land invasion of Honduras.
For Britain's handful of Colonial Army companies and several thousand colonists to resist Mexico's army would be nothing but a fool's dream.
Moreover, Mexico had ample reason to attack Honduras. Honduras itself had once been part of Mexico, and most fatally, it possessed veins of gold and silver.
In this era, no country could resist the temptation of gold and silver.
Even if Mexico feared Britain's strength, merely pulling little tricks all day would be enough to give the British a bitter taste of their own medicine.
As the saying went, it was not thieves stealing that one feared, but thieves setting their sights on you. So long as Mexico was shameless enough, the colony of Honduras would follow Guatemala's old road to ruin.
Besides, having Santa Anna purchase Guatemala was also meant to divert his attention. Otherwise, the Mexicans keeping their eyes on the Austrian Empire's California all day was quite a troublesome matter.
And after losing Guatemala, France would have no