Should we arrest people for, say, agreeing with the points made by terrorist organizations? Or alternately should we not arrest people for providing material support to those organizations? According to your logic, if we consider one action far more dangerous and reprehensible than the other, we're erecting a "mystical dividing line."
Well first, you're talking about a legal matter, and one that directly affects life and death for US troops. That's pretty different, and I'm not even talking about arrest or legal consequences, just whether or not people deserve judgement based on arbitrary lines in the sand, or if we can be mature about it and recognize that not all similar actions deserve the same criticism.
Second, that gets into the messy area of whether you've donated to an anti-gay organization by eating at Chick-Fil-A.
Let's say one person goes there because they like the food and have no idea about who the organization gives money to, another person goes there despite knowing because they don't feel that strongly about it, and another person goes there specifically to support them because they agree with their corporate policy.
If you want to judge people strictly based on where their money is going, then you have to either condemn or condone all three of them (and I'm not arguing in favor of either, just that it's one or the other). If you allow for shades of grey, you could say that person who is intentionally going there in order to give money to an anti-gay organization should be judged differently than the others, and maybe the second is less guilty but still worse than the person who doesn't know.
I think there's room for that. I think we can look at specific circumstances and say "yeah, this is worse than that," and not need a hard line.
Because like I said...a vocal, outspoken bigot, vs. someone who doesn't make their opinions known at all and drops a dollar in a bucket...