I don't agree.

FB can still side load apps all they want, they just can't do it on an enterprise scale like they currently do because they've abused their enterprise agreement.

This is not different than abusing (say) Microsofts MSSQL to host on a 10,000 core machine when you have a 2 core license.

"Who really owns the phone" is a misnomer, because you've licensed the OS. The physical hardware is of course yours but the OS remains property of Apple, your data remains the property of you. This is especially clear if you take the time to read the EULA. (Although EULA's have questionable legality in many parts of the world)