If that boss is of the opinion that you unnecessarily escalated the situation, you can easily get the troublemaker label completely on your own, plus get some b

If that boss is of the opinion that you unnecessarily escalated the situation, you can easily get the troublemaker label completely on your own, plus get some bad faith from the accused party if said boss talks to them. In my opinion, this depends a lot on the severity of the issue anyway. If we're talking about workload assignment or some comments, talking directly will be the best solution. If the issue is serious (sexual harassment, academic fraud etc), directly escalating is warranted.