BTEC offered, but worried over university prospects.

My son has a mixed bag of GCSE results - although he scored a B in English, 5 in Math and C in Science, unfortunately he fared poorly in the other options (DT Graphics, French, Geography) and hasn't got the required 5 A*-C. We are really gutted over this as he has worked hard, despite various challenges. The school is now offering him A level in English Language, Math Studies (Math AS) and BTEC in Business Enterprise and Enterpreneurship. Our original choices for A levels were Economics, English Language and Math. They can't even play around these choices and flatly refuse A Levels, except in Language, purely because he doesnt have the golden 5 GCSEs. They think a re evaluation won't help either.
My concern is that this will affect his university prospects as he would like to pursue Business Admin/Management in future. These grades do not reflect his potential and academic aptitude and he is depressed that he's being denied an opportunity to turn things around. He is also bothered by the prospect of his peers making fun of him for doing a BTEC. Is there any way the school can offer him A level options further down the term? If not, can he apply to most universities with this BTEC/A Level combination? Will his GCSE grades come back to haunt him then?
We aren't from the UK, nor very familiar with the system - we can only go by the school's assurances that this is the best option for him. However, we aren't convinced this is the best route. Please offer your comments and advice.
Thank you!