AITA for saying something is cowardly

My husband and I are going through a divorce. Right in the middle of it, we’re also celebrating our daughter’s birthday next week. My parents will be visiting and staying with us for several days. They know we’re separating. The other day my husband and I were discussing their visit when he mentioned he’s thinking of staying at his mom’s while they’re here. I said, “that’s a cowardly thing to do.”

I know this is not a kind thing to say. I wasn’t focused on being kind or mean, just wanted to express this opinion. My husband was furious that I said this. He says it is simply something wrong to say. I don’t know that I’m convinced the statement is just “wrong to say.” While it’s not particularly nice, it is an opinion and one I wanted to share. I did not call him a coward, which I believe is a big distinction (he disagrees), but I do think that action would be cowardly.

Anyways, curious what the internet has to say. Is that phrase inherently wrong to say?

As additional info I’ll add that I do care about hurting his feelings. He hasn’t admitted it, but he’s obviously hurt. I can totally understand not saying something because a person is hurt and my focus wasn’t on hurting him. I don’t, however, care much about whether he’s angry. He has a history of blaming his anger on me and so I’ve grown a bit indifferent to what “makes” him angry. He says he’s angry because what I said is “simply messed up.” Is it? In this context I believe what I said is true. I was trying to communicate that because I am hoping he will be “brave” and face my parents. So is it horrible to communicate that opinion?