James might have agreed with Remus if not for the other aspect to the plan that Sirius explained. And as it was Sirius's plan, he should be the one explaining it. He didn't want to draw too much attention to themselves from the Death Eaters just yet, only enough to catch the attention of the Order, wherever they were.
Well, and he did want to grind a few Death Eaters into the dust, even if they weren't the ones that had killed Dumbledore. He didn't know who had done that, so he actively resented all of them.
"Hey, Peter," he said, grinning at him to make him feel less nervous. Really, they could do without nervousness around each other, especially in this context. They had bigger things to worry about, and they needed to be united. Completely. "And, yeah. I think it's worth the risk. They might need people at Hogwarts next year, if things get bad there. That leaves us the summer to find a way to get in touch with them."
He didn't even know who 'they' were, just that there were people out there that Dumbledore had mentioned. James had been counting on Dumbledore to connect them with those people when it became necessary, likely when they graduated. Things had gotten bad faster than even Dumbledore had anticipated (so far as James knew, anyway), and so they needed to take matters into their own hands.