Norm, it seems that this is a sensitive triac.

On page 2 it says that for a trigger pulse of 1.3V and a 100mA current the holding current of the load will be 5mA only.

But as you can see it needs 100mA trigger pulse!

On page 4 on the top diagram, there is a relation of the temperature to the holding current, which fall as the temperature rises.

To seems more appropriate to drive it with a small transformer, so that a 5V pulse will be lowered to 1.3 but with an increase in current drive. A 5V at 20mA will be transformed to a 1.3 at about 70mA.

HTH,
Ioannis