IMO making an accusation with your main account holds a little more credibility with the accusation. Of course, it's definitely still going to depend on the evidence presented, but if the evidence is solid and the person making the complaint is a reputable member, I would give the accusation more credit.
As coolcoinz said, new account is not equal to false accusation. We should rather look at the evidences provided if any, rather than the age of an account. I have also known a situation where complete newbies locate this forum through search engines when they run into troubles with casino.
I don't think it's necessary to base it on the account status here. Newbie or hero, they're the same, and when someone makes an accusation, we don't evaluate it based on the reputation of the accuser but on the evidence presented. If it appears in our minds that when someone with a higher rank and good reputation in the forum makes an accusation against a certain casino, even without enough evidence, we would already side with them, then that is not fair and not how the forum works.
We are almost saying the same thing from different points of view. It will be beneficial if we also understand the angle Yahoo is coming from. In as much as all accusations depend on the evidences provided, we should also not forget that in the ambient of the forum, reputation and trust is important. Not necessarily about the age of the accusing account here, but the reputation of the account.
I can stumble on some random accusations by newbies against BC.games, skip and move on. But if such an accusation is made by yahoo62278, I'll likely not skip. I have to read the accusation and it will take the project owners not more than 24hrs to clear their name. That's the angle yahoo is coming from.