It is only as weird as eating at any restaurant alone.
And if you find eating at a restaurant alone weird you are likely either overly judgmental or overly sensitive to what other people think given the myriad of "normal" reasons people would do it (like the one in the OP!).
And if you find eating at a restaurant alone weird you are likely either overly judgmental or overly sensitive to what other people think given the myriad of "normal" reasons people would do it (like the one in the OP!).