I imagine a haki user may be able to penetrate the barrier, but it depends on the strength of Bartolomeo's barrier vs the haki user's haki. It's not like the barrier suddenly becomes paper in the presence of haki. That would be like Luffy being able to just flick a hole in Monet's snow prison with haki on his finger.

However, Bartolomeo's barrier has to be pretty damn strong to effortlessly absorb an attack that would kill a Yonkou.