Sorry for confusion. Commit filtering are YAML-only settings and therefore are not available with REST API (even if you get or update settings in YAML and not JSON). So to take benefit of this feature, you project should use YAML file for configuration.
We do not have plans to expose this feature in UI, at least in near future. There are many features like this or this which are YAML only and their number is growing. Generally we treat UI configuration as good place to start and when people need more sophisticated configurations, they switch to YAML.