I don't think having excessive bankroll is of a bad implication to that extent, except if the gambler involve is not willing or able to make things go right as wanted or expected,
The word here is not willing, when your not willing and eventually your having way too much or what to you might be considered too much as your gambling bankroll, you get it out. Just like we have in OP. It it weren’t for the fact that, it was a deposit and the T&C requires you to at least wager 1x of that, OP would have gotten it out. So, if you ain’t comfortable having way that much for a bankroll, it doesn’t matter if it were the slightest discomfort, just opt for a withdrawal.
Any bankroll that's above what the person can afford to lose is bad in my own definition of playing safe, and on the situation of the Op, I don't know how big that money is to him or her, but judging from the intended amount he wanted to deposit, it's obvious that $900 was excessive, which is pretty big compared to what the initial budget was. The only time it will become a good thing is if the Op manages to turn it into something big; if not, I will say the risk is just fucking too high.
There is a catch from having way much for your bankroll and that is; you tend to gamble even more. Why the hell not? You have way enough money for it so, what’s stopping you. Besides, there is a wagering requirement and you ain’t getting that money out until you archive that.