Your reference to BH was a little strange. It is a very successful group and I would say that they didnt become so successful by throwing money away or buying into companies or ideas which are unlikely to make money.
So, I would rest assured that NJ has excellent backing.
Safety of your job, you take your chances with any company that you join these days and NJ is no more of a risk that anything else, perhaps less of a risk because the economic downturn which the world is experiencing currently tends to effect the very rich (NJ customers) less than the majority.
Your seniority with NJ, it will be around the 1000 pilot mark if you join, but you will be at the bottom of the list of whatever company you join, so that shouldnt be a factor.
To be honest, your reasons are quite weak and I would rather recommend you look at the package NJ offers and if it suits you take it, if it doesnt-dont.
Fairly simple in reality.