No, that is just for timing purposes. Too much is being read into that application (as discussed in detail here)According to wikipedia, it says A Track Access Application made by Grand Union Trains to the Office of Rail and Road also cited the possibility of the use of Class 185s on services between Oxford and Bristol. But I'm not if it's true or not. It could be a rumour or not.
Put simply, the application by Grand Union needs to be considered against all possible other uses for the paths, including uses that aren't committed because there is no point offering track access to Grand Union if it disrupts better uses for the capacity. There is no commitment at all to run Oxford to Bristol and even less to use 185s - they are simply a convenient train class to base the timings on.