never ever post ANY child grooming pics online in a forum. Even if you do blurring, swirling all sort of picture manipulations - becuse they can be all de-manipulated and infact there are many, many child p*rn darkweb sites where precisely this kind of cyper-based pic manipulation is used to post pics, so its very hard to prosecute and de-cypher the swirled image.
Even if you are harmless in this and just an outraged citizen, you will FOR SURE be on the radar of authorities for this, since this is pretty much the only thing, other than internet fraud/wire fraud that the authorities ever spent any dime on in terms of internet crime and this is BY FAR the one they look at most, because the success stories are such huge headline 'win' for the authorities.