If we were to ignore the 5 btc loan request then that is true, you can't withdrawal your client's funds on bitmex, but you can make it disappear in a few bad trades, so technically thier BTC is at risk, it does not matter if you withdrawal it or lose it.

You could very well be legit and not willing to get rich by risking people's money but unfortunately most bot's creator are scammers who go by the rule " if the bot wins, i win, if the bot loses, who cares ?" - so you should not be surprised that people will tag for you this, think of ICOs, there are probably plenty of legit once out there, but what are the chances?   

Your reputation and rank matter too, you are not even in a position to trade 50$ worth of btc without escrow, let alone 5 btc loan.

I am not trying to be mean, I just don't want you to feel bad, nothing personal here, we just learned from experience that promises like yours are usually never kept , and people have lost millions of dollars trusting random people with random trading bots, we are only trying to protect the newbies by being extra conservative, some innocent users could be victims to that, but that is life !.