There is plenty of precedent for honours being subsequently removed when bad stuff comes to light, the most obvious being Savile. In his case, there was evidently some disquiet about the granting of the honours in the first place, among some who knew him, or knew his reputation. It is right, I think, that the nation shouldn't honour a person who has been found to have significant flaws, despite whatever positive acts led to their nomination. There's a balance to be struck, so there's a line to be drawn.
The question, then, is where is the line to be drawn. Clearly predatory sexual behaviour is way beyond the line, as would be embezzlement or a flagrant disregard for the law, IMV. Less clear-cut are the sort of character flaws which seem to drive some people to particular success.
In the case of Boycott, there is a specific incident for which he was tried and found guilty. There is also a tendency toward aggression, verbal and otherwise, which might lead one to reasonably wonder whether the incident in question was an isolated one. People honoured by the state are, in a sense, being held up as role models. It is not simply a transactional process - reward for services rendered. That's why it is right to remove honours, even if the services were indeed rendered.
So the question here is whether, given the history, you could or would hold Boycott up to be a role model. My feeling is that, since he continues to deny the offence, and has continued in his irascibility, he falls short of the standards required of a role model, so the honour is inappropriate.