Less damaging to who?

If there is a good reason for a double in the greater context of the war, then who would have a problem with it?

If there was an operational need for our enemy to believe Trump was at the rally, why would any Trump supporter have a problem with it?

Do you really think Trump supporters would be all "yeah, I understand that it was needed for operational reasons and it helps us win the war, but I'm still pissed that I was used in that way even if it helps us win the war"?

If Trump was off playing golf while a double held a rally, well that's one thing and I would understand people being pissed. But if he was, say, making a secret trip to Gitmo to give evidence in secret trials and it was important to make it look like he was standing in front of tens of thousands of people at that time, would anyone really mind in the long run?

This all assumes that it wasn't the real Trump. This is just a single post/image, so I'm not sure.