I don't know how Sullivan's deal is structured as to whether or not he was paid during that time his was MIA or what but, in any case, at this point in his career, my guess is that his current deal is probably worth around 300K, so a fine of 100K is pretty significant.
WWE is still gonna look bad though as it seems pretty obvious they were hoping this would just blow over and disappear after a few days rather than gain steam the way it has. Another reason it'll look bad is because it's going to look like the Mars company, which is the company that makes Snickers candy bars and is one of WWE's biggest sponsors, had something to do with getting WWE to hand down this fine. Someone from the company did talk to WWE and the reports have some politically correct statement and my guess is that the actual statement was more along the lines of that they punish Sullivan or WWE would lose a big sponsor.
To be honest, I wish WWE would just stop trying to paint itself as this benevolent, forward thinking, progressive company that seems to dish out harmony to all the world because it's long since become apparent that all the various PSA announcements, community outreach programs and charitable partnerships are little more than marketing. In actuality, I don't think most of the WWE brass gives two shits about any of it aside from all the good publicity and money that comes with it. After all, as I said, they were probably gonna let this thing with Sullivan slide altogether if it hadn't kept getting attention, they're doing business with Saudi government even though the government has a decades long history of human rights violations & murder, bullying was taking place and, allegedly, even encouraged by Vince McMahon such as JBL's actions backstage even while the Be A Star program was in high gear, etc.. Of course, I know WWE will never do this as they have too much to lose and Vince has invested far too much time and effort into building this charade; still, at least they could say they're honest as to what they're all about when the cameras are off.