"careful, don't go broke now"

[BluffTHIS!]

As others have said, he clearly wants a check or cheaper bet from hero. But a lot depends on how much of a calling station he is on the river with weak As or middle pair (or QQ here) which hero didn't specify despite saying he was "live". And all the advice here advocating a push really runs the risk of losing all action especially after that comment by the old guy. So it goes back to the rule of bet how much you think he would call, which can only be determined from his previous river calls, although as a default I would bet 1/3-1/2. I would only push here against players whom I thought held a stronger hand or would interpret that as a desparation move by QQ and be more likely to call with a weak A.