There's always two sides to any tale of woe.
The odd thing about bullying is that people who do it usually don't realise they are committing it, or have been subject to the receiving end of others having a laugh at their expense themselves & thought nothing of it.
Doubtless, the person that took it the "wrong way" sees it entirely different to the perpetrators, otherwise they would not have felt the need to have complained. If there was nothing in it, the college would simply have investigated it & found no evidence, nor felt the need to have taken any action against a "load of lads".
The Royal Marines do not tolerate bullying inasmuch they do not permit anyone to bully you & neither do they allow you to bully anyone else. With regard references, we will usually request a reference from any educational establishment you have attended in the previous 2 years before your application.