A comment on the thread from the code's contributor is super useful: SPECK was added because on low-end Android devices with less than 50MB/s AES, it enables phones to have encryption enabled by default. That is, SPECK is useful in cases where the alternative would be no encryption at all.

I'd be a little surprised if SPECK was the only workable answer here.

Later:

It isn't; Google is doing HPolyC instead.