I feel that joining a private group under false pretexts is an underhanded player (distinct from character/CMDR) action that should be punishable like any other underhanded player action.
However, I can't help but think giving special attention to specific private groups for the purposes of fast-tracking reimbursement is a double standard, a waste of support's resources, and potentially subject to abuse.
When it comes to Open assaults by CMDRs upon other CMDRs are both inevitable, and to an extent, desirable. Frontier has chosen the rules they have because the setting they are trying to present (to various degrees of success) is
not safe. Ultimately the survival of a CMDR's vessel is going to come down to that CMDR's actions or inaction.
Regardless, I highly doubt there will be a radical restructuring of the modes, no matter how many CMDRs happen get themselves shot down while participating in DW2.
Fortunately, nobody needs to defend their choices to you.
Choices that involve breaking the rules in shared multi-player game can't be defended.
You can't have a game without rules to define it and allowing each player of such a game to define their own personal set of rules that conflict with how the game is intended to function undermines the game for everyone. If someone has a problem with the rules, they can suggest a change. If someone finds they cannot abide the rules, they can refrain from further play.