I agree with @dawn that none of the responses are meant to beat anyone down.
You are right with respect to there really is not a reason to oppose handloaded rounds from a legal standpoint unless you are making rounds that may be prohibited by the laws of the US or some states, such as armor piercing rounds. And, as I mentioned, handloaded rounds may be much better than anything you may get off the shelf, especially if they are loaded for a specific purpose.
That said, in light of the Second Amendment, there is no reason to oppose open carry from a legal standpoint. There is no reason to oppose concealed carry from a legal standpoint.
All of that is true until you put impanel a jury. Juries are made of people and will be persuaded one way or the other by the arguments of your attorney and the prosecutor. Once a case goes in front of a jury, you not only deal with the law, but with all of their feelings, biases, prejudices and perceptions, good, bad and ugly, of each juror.
With that in mind, as an attorney what ammunition can be used against you from a legal standpoint even though the ammunition is perfectly legal to use and carry. That is why I would never recommend anyone ever carry Hornady Zombie Max as their self defense ammunition and why I do recommend carrying ammunition manufactured by nationally recognized manufacturers.