I think I can see why it is good to call this. The pot odds are 2.1:1 (32%) and your odds to complete the flush are about 36%.
But why is it a good idea to raise or even shove?

Even at 40% equity is it +EV to shove?

The cut-off would be:

0 = 40%(B+P) - 60%(B)
60%(B) = 40%(B+P)
20%(B) = 40%(P)
P = 3.8
40%(3.8) = 1.52
1.52 * 5 = 7.6

The pot stands at 3.80 and Hero has $9 left to bet with.

EV = (.4) x (3.80 + 9) - (.6) x (9) = 5.12 - 5.4 = -0.28?

Also, there is the whole fold equity thing that needs to be factored in as well isn't there?
I'm not quite sure how to do that but the details are here: How to analyze all-in