When the victim filed the police report in June 2019, last year's finals, which were also in June 2019, might not even have occurred yet. And even if the report was filed after finals, the victim might not have heard Drew won by the time she went to the police. I'm not sure how locked down the results are, but I think most of America found out in September when the finals aired. People in the ninja network aren't the average viewer, but do the secrets travel or are they kept under wraps well?
Personally, I don't find the timing suspicious at all, whether Drew hadn't won yet when she filed the report, or she just found he won. Also, if Drew was the newly-minted winner of $1M less taxes and someone is after money, it's a gamble to go through all of this like his assets aren't going to be depleted on defense lawyers anyway. And they will be - he's not going to risk staying out of prison with a budget lawyer or decide not to spend money now so he can save it for post-parole (if he does go to prison).
Regarding why there was quite some time between the abuse and the police report, the various news articles have a statement in passing about how the mother did not originally go to the police because the daughter threatened to harm herself. In reality, experiencing it, that kind of emotional turmoil is not in passing. I'm sure it was a lot more dynamic and involved. It seems obvious to outsiders to go to the police and go immediately - and some people do - but not everyone does, and they have their reasons for it. Some people feel like it's just going to make everything worse or they'll be blamed, and that's the last thing they can handle. Sometimes, with the distance of time, they are in a different headspace where they can take that step. And even though the mother was the adult with the responsibility of advocating for her daughter, especially when her daughter couldn't do that for herself, going to the police might not feel like an option if your child is not in a good place mentally and actively doesn't want to tell the police anything.
Also, many people who have been abused don't recognize how bad the abuse was until they're older. This is true with full-blown adults, and it's certainly true of younger people who have been groomed and abused. So I don't think it's at all odd that a teenager who is 18 and more removed from the abuse starts to really understand for herself what happened to her at 15+, and now wants to do something about it.
One more thing about the timing - whether it's seen as suspicious or not, the timing of the report really seems to have no bearing on the evidence the prosecution gathered and cited in the criminal complaint. The timing of their interaction and evidence is what matters. There's no concept of whether the content Drew had in his possession and the messages between them were okay, depending on whether they were in a consensual relationship. By law, she's too young, period. Does it really make a difference if she filed a police report well before Drew won ANW? Does it change what the evidence is illustrating? Maybe to some, it changes the perception of where the victim and her family are coming from, but that doesn't change the evidence.
(In case you can't tell, I feel very strongly about the nuances of sex crimes.)