If Matias can catch him he definitely could hurt him but I imagine him not cutting down to 35 will not only help his physical strength, but probably make him more sturdy.
Mattias is a death by volume puncher /
and death by blow puncher (literally), the latter a result his ability to arm punch in volume during the middle to late rounds. In some ways he's similar to Lomachenko from a suffocate the opponent and break their will perspective.
Haney's great on the backfoot, close to Shakur in this respect, but at times he's shown a noticeable tendency to get overwhelmed against middle to late round volume punchers (eg Lomachenko, Linares to an extent, he hugged his way home.) There's moments in that fight (Lomachenko) where he's close to getting stopped, but to his absolute credit, he bounced back in the last round.
I really like Haney, he's an exceptionally determined and dedicated talent, he really embarrassed Prograis, which is harder than he made it look.
A fight with Mattias would be huge for boxing aficionados.