I truly don't think Mr. Silverman/the admissions office would have said group 3 is the largest without that being the case. I trust that everyone is being honest throughout this process. I know in threads from a few years ago, one or two people did self-identify as group 3. It's important to remember that SDN is a very small subset of applicants and is also probably fairly self-selecting both in membership and in who decides to post. Individuals who are in group 3 and are active on SDN may just not have posted that particular piece of information for various reasons.
As avgn suggested, given that group 2 was only reached in the last week or two, it's probably not looking awesome for group 3 this year.