1. Some people trust SHA more than Scrypt
As a KDF? Can you provide some evidence for that?
I've never seen someone suggest that but perhaps they should.
In any case it absolutely should not use SHA512 as a KDF. SHA512 is a hash function, not a KDF, and it does not make an acceptably secure option.
If instead you were saying PBKDF2-SHA512, okay but probably not worth the complexity to include more mandatory code.
2. Scrypt is hard on embedded devices. SHA isn't.
The parameters selected should work on embedded devices. And with the support for delegation it doesn't matter quite as much if the selected parmeters didn't work on some device.