Please do not take their assessment seriously; secondly please consider other training alternatives, please do not fall for marketing hype and lies and lastly, please do a lot more research before you embark on training.
To give you an idea .. I had the opportunity to take the assessment at OAA. I passed every section with flying colours except the hand-eye co-ordination and was told I did not have the aptitude to fly a helicopter. I had a CPL(H) at the time!!
There are many training schools other than OAA and I would suggest you look at modular training.
To answer your specific question, I doubt an airline would even know about your failed assessment, much less care about it.
Cheers
Whirls