Labour has freely admitted that should some disaster occur and they got in then they'd try to renegotiate a deal with the EU that, if successful is bound to be worse that that already achieved, in order to put it up against ignoring the public's decision to leave in a further referendum. No rigging required, merely ignoring what is right & decent achieves that.
As for a state of panic; hardly. It's just common sense not to get complacent with the polls, and point out a possible nightmare alternative.