Urged my teacher to reconsider...

Is it rude to say "I urge you to reconsider your decision regarding X [event]"

In this situation I have been unjustly denied access to a trip due to time off of school that occurred due to a disability

I didn't think so, but I emailed my head of sixth form urging him to reconsider his decision and explaining that when I have talked to many universities about my specific situation, the personal statement becomes much more important than usual and that this trip would provide an excellent opportunity and an amazing experience etc. and would look very good in a personal statement. He came back stating that 'we do not have the type of relationship where you can "urge" me to do anything', for reference I am also Autistic and have multiple disabilities, he is aware of this and to me "urge", is not rude, rather, it is strong language which in this context is designed to ask the recipient to scrupulously reconsider due to the connotations of their decision. I had also made it very clear that I was only urging him due to the university situation. Any advice? I still really need to go on this trip but he also stated "The xyz issue is closed, but I will make it plain why for one final time."

Also, does anyone have any advise on my rights regarding this? as it is a discretionary trip but the criteria he used for the decision of who could go, I could not possibly have met... due to disability related time off. If anyone has any advice on this also it would be useful but I know that this is an English forum and that this may not be available.

Thanks

Anon