I'm working on a project which will compile user input data over a course of time and then will be reviewed by a third party. At current my intention was simply to have the users visit the third party, hook their device up via USB and send the data via a command from the device. The more I look into it this seems like it cannot be done so I was just looking for some clarity on the matter.
Can android devices push files onto PC at the behest of an app?
No, that is prohibited. The only way around is to have an application on the PC site that manage this. One tip, don't bother around with the MTP stuff. Just write a WebService for your third party and enable the user to upload its data there.