Who said it was unwarranted? I do think it would not be cost effective. As cold as it may seem, it comes down to the math. Could same cost have more benefits used elsewhere? Without knowing the particulars, I'd tentatively hazard a yes in this case.
The same amount of money could be used for carefully targeted low cost safety improvements over the entire town, with a larger overall safety impact.
For example, I'm working on a high risk rural roads funding application that will treat a dozen sites for about half the cost of a ped bridge. In the 5 years I've worked at my county, we've had no pedestrian fatalities on county roads, and 10 run-off-road fatalities. Despite the fact that I have long been a bike/ped advocate, and participate with our MPO's bike/ped committee, I'm going after the single vehicle lane departure crashes. Why? Because they are >80% of our fatalities, compared to 0%.
"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928
"I'm searching for the questions, so my answers will make sense." - Stephen Brust