How should one react when one's work is rightfully critiqued during a conference presentation?
Should we accept that


Yes.

If somebody points out a flaw in your work, be thankful. They are giving you free advice. Don't try to be right at all costs. Of course it's awkward when people point out major flaws in your work when there is an audience, but it's part of the game.

If you believe you are right, defend your point using objective arguments. If you know the critique is founded, accept it and try to make the best of it.