According to the post, forest experts from the college made the 100-plus age estimate "based on the tree's size and growth characteristics".
It could be. BSU was established in 1916 as the La Trinidad Farm School. For the narra tree there to be more than 100 years old, it should've been planted there between 1916 and 1926.
If you ever pass by the tree there, go for a closer look. It's a magnificent tree. Especially with its golden-yellow flowers.
Narra trees are considered a threatened species in the Philippines.