Yeah I can't see that would help.. It's not bracing anything, it's deadener. You can put it in any shape you want it's not bracing a panel so making it shaped like a brace isn't changing that. Anyway deadener can def help roof flex, but it doesn't eliminate it.. It mostly drops the frequency that the roof moves on down. I prefer a mixture of bracing and deadening on the roof. Brace across the roof horizontally about 3-4 spots, depending on it's length then a layer of deadener in between your bracing. Double layering deadener is a huge waste.. I've done it myself, but it's a bad idea. Since your not touching metal you just deadening your deadener. 1 layer is enough.
Anyway bracing raises the frequency that flexes the roof higher. Deadener lowers it, but the combination lowers the actual amount of flex the roof will see down so much that the actual frequency it moves at doesn't matter anymore. Especially with 4 braces on a standard small to medium SUV roof. What i do is get 1/4inch wood so it'll bend to the roof countour, then glue it in place, then stack 1 or 2 more 1/4inch layers on top of that making a very stiff and strong 3/4 thick layer, it actually sets up and is stronger than 3/4 would would be of the same material, but it perfectly fits the roof.