I can see where some people would find that to be anti-Bush, even if the fellow had no intentions of being anti-Bush.
However, if the city ordinance or whatever had enough complaints, even those that weren't really valid, they would be pressured to have the man remove the sign. This is similar to that girl who was going to wear a tuxedo to prom but was denied due to the dress code (and not because she was a lesbian, although people wanted it to sound that way).
The only thing I could guess at (and this is still a reach) would be the word "KILLED" in red. Written in red signifies that there is a more hostile sense towards that word than the "IN IRAQ" part of it.
Red perhaps meaning opposition...or it could just be a word written in red to show how tragic the situation is. There is obvious emphasis for the word to stand out.
That's all I could think of to address Feceman's statement.
I see no way that could be considered anti-Bush. Notice that he's also got those ribbon-things with the flag and that say "support our troops". Not many anti-Bush people, in my experience, have those. The sign is just for that purpose -- to support the soldiers and to show respect for those who died by memorializing them.