They're both right, in their own way. Jack is right to remain overly wary and cautious, and Sombra is right to be in a rush to get the hell out of there. They're both right because they'll need all of their combined instincts and skill to get out of this alive.

Defeating Reaper isn't necessarily hard, but it's not easy either. What made it 'easy' is that he didn't take massive risks beyond his capabilities. He knows when toeing the line becomes straight up launching himself over it. Right now, he doesn't recognize that line. All he has is a zombie-like drive, forcing him onward.

What normally would've kept him down, or encouraged him to retreat, doesn't do the trick. The bubbling intensifies, the smoky smell of flesh and blood filling the space rapidly as it starts to expand. Regenerating is no easy feat, and time-consuming, not to mention incredibly gruesome in this particular form. It's no quick and dusty swirl of particles that once used to be his body, oh no— strands of white and gray veins, slick and organic begin to bloom from the surface as his face begins to slowly stitch itself together. Hopefully by then, they'll have thought of a better plan than to stand there and yell at each other.