Tradestation is it's own brokerage and their platform is for their clients. I wont definitively state it, but I'm fairly certain they arent going to allow another brokerage use of their platform like some 3rd party, such as NinjaTrader, but maybe I'm wrong. I use Tradestation daily.
I assumed he was thinking Tradestation's platform is like Ninjatrader which I know allows the use of their platform over different Futures brokerages. I wasn't completely sure the Tradestation platform was proprietary property, but was pretty sure. I can understand his want of the platform though. It is top notch imo.
Tradestation int. uses IB data which is notoriously bad . There are also other things like higher commissions.. Unfortunately there is not currently available any good TS-IB bridge. Slow smtp protocol which give up any control of your orders, no advance algo available etc. It may change soon though.