He will be damaged yes, but he is not in front line politics anymore, Sturgeon is. If these accusations are found to be correct then If, and If,mind you Sturgeon knew about the alleged assaults and sat on it her credibility would be in shreds.
Obviously this is just an opinion, but it could get very uncomfortable for her. There are people with an agenda against the SNP who will most likely cast aspersions of the ilk that she knew and the mud may stick. After all as the media like to practice," why let the facts get in the way of a good story."