Given the severity of the charges, it would be better for the club to keep Gelling on a lower profile.
Using him in promotional material with these charges hanging over him is a deliberate choice and it looks provocative. The promotional material is about building the club's brand. A certain proportion of the target audience who sees him being used the promotional material will have a negative reaction so it is counter productive. There are plenty of other players who could have been used in the material that wouldn't have the negative associations and so would be safer at this point to promote our brand.
I agree that he is innocent until proven guilty so it is fair to honour his contract, allow him to participate in training and be eligible for selection in games, but discretion should be used when it comes to using him to promote the club.
The same principles of British justice apply to Prince Andrew who has also not been found guilty of any crime. However, he has been discreetly removed from making public appearances so he is not promoting the Royal Family or the UK.