Allow Rule Load to Profile Picture (IMAGE) Field

There is a field name on Person called Profile Picture of type IMAGE, same thing on User. If I can get to a source photo file via SFDC or even Community hosted online, e.g. a URL with a .jpg extension, I should be able to use Rules to load images to these. In fact, a Slack integration creates a Slack Staging object which has a Image URL (String) field - would love to pre-load these into the User object. 

TL;DR: allow us to write to Profile Picture fields on Person and User via Rules!