Because the image essentially has no colour [black/white/grey are not considered 'colours' for this] then Preview cannot do anything useful with it.
You can make it swing the tint between greenish & blueish, you can even then force a white balance change to make it bright blue – but you can't squeeze a red out of it this way.
pixlr.com, on the other hand, seems to have a much more Photoshop-type editing suite.
From this you can use the Fill tool [paint bucket] to block replace colour. Note that because the masked image is actually mainly grey but has a bit of white on the edges, you do this by first painting it all white, then when you paint it red it will use the entire shape…
Note the background is actually transparent, so you will see though it to whatever colour is underneath [so long as you keep it as a png & not transcode to jpg].