This makes good sound sense to me, to be quite honest.
The OU is going to lose a substantial number of paying students as a result of the changes to funding in England. So we've got revenue streams to look at that need to be bolstered.
The average "Online" degree fee is pretty extortionate if it's from a reputable university (it's not much better if it's from a disreputable one like the University of Phoenix).
The OU's got a damn strong rep behind it for rigour and is widely viewed in a positive light in many corners of the world (even Asia's beginning to notice it and appreciate it more than might have been said to be the case in the past).
For the OU to invite international students to pay fees equivalent to (new) English students could arguably be a pretty decent coup.
Mind you, it could just as easily backfire...