Well, for one, the discussion in this thread on these boards has given me that impression. Plus a number of comments in this thread and from various news sources.
If they had thrown a rope with a noose over a tree branch or something similar then I would say that was a different situation. HOWEVER, whether it was symbolic, functional or simply incompetent in its construction there is no doubt in my mind it was a traitorous, horrific and despicable thing to erect on that day, at that place.
Honestly, I doubt Pence would have been alive by the time they got him to those gallows if they had been able to get their hands on him. Someone already said they would have likely torn him to pieces. The intent of members of the mob was undoubtedly to cause him serious injury or death.