I'm interested to know whether people think a figure should have an honour or something similar witheld or even stripped on the basis of allegation.
I'd say, in the former case, yes; in the latter case, no.
In the case of Kevin Spacey, if you are going to give him an award, it would be better to wait until the allegations are resolved one way or the other. If nothing else, the cloud hanging over him will dampen the atmosphere.
On the other hand, I think it is perfectly reasonable to strip an award from somebody who has been convicted of a crime. This sometimes happens in the case of British Royal honours. But it is unfair to strip such awards until they have been found guilty.