I don’t see it like you at all. It is very much akin to walking with your wife/GF then proceeding to whistle at another attractive woman walking by in the street. - well, it isn't though.
A catcall is public. A "like" is private - you'd only know he had "liked" something if you specifically checked. Why would you check? Surely it doesn't matter at all. Not enough to snoop around?
A catcall is designed to invade the space of a woman who is just going about her business in public. A "like" is intended to privately show appreciation for a publicly shared image.
A catcall is meant to make the subject of the catcall, as well as other women around, feel degraded and exposed. A "like" is intended to make the person sharing the post feel validated.
I think the only thing that's similar about a catcall and a like is how YOU feel about yourself when your partner isn't 100% focused on you.
I find it disrespectful and my DH would feel the same.
It's only disrespectful if "showing respect" = "my partner isn't allowed to appreciate any beauty except mine, even if he does it in private" which to me just reeks of a woman who needs to be pandered to in order to feel good about herself or her relationship.
I just feel sorry for people who are so reliant on partners' undivided attention in order to feel safe. It seems like a house built on sand.
Plus I love seeing and liking pictures of beautiful people online, weird to think that that somehow "disrespects" my partner. It all sounds exhausting.