Was the execution of José Rizal justifiable?

Given his antipathy toward the Spanish colonizers, and his support of the nationalist rebels, it was natural that the Spanish (even the church hierarchy) wanted to get rid of him, and tried to justify it. They might have feared making a martyr of him, but not as much as they feared him in life. Executing a charismatic leader did make things marginally worse for the Spanish, but in 1896 their prospects for keeping the vestiges of their Empire were not good. Two years later, they lost the Philippines to the US in one of the shortest wars in history.