That is my interpretation Rufus. Oddly in however many years of playing 5th edition I have had, this has only just started to come up. I always put my characters into hand to hand, because they are pretty much always the most useful model in the unit. Most fighting heroes tend to also want to be in the battle.
However with blood angels attaching relatively weak fnp generating medics to units or more generally chaplains with hammer armed terminators, they usually don't want to get them into hand to hand. If I charge them, he has no choice, he has to get stuck in, but when he charges me he can choose not to fight. Seems all kinds of stupid.
You could deliberately exploit that rule with imperial guard too I believe. Attach a preacher to a unit of roughriders. They charge as cavalry, he has absolutely no chance of making it into hand to hand and thus cant be killed, but his bonuses will still apply. Crazy I tell you!