Yes, I know it stands for GNU Image Manipulation Software.

People in general don't know that.

When they hear gimp, they think of a fetishist in a gimp suit, or a slur for a person with a severe disability.

Both are bad. I also wouldn't have my software share a name, even as an acronym, with other slurs or fetish stuff.

Imagine you're a manager high up in a company. Someone comes to you and says "sir, I really think we should be using PAKI instead of [proprietary software alternative]", and have you considered PISSPLAY instead of [proprietary software alternative]?"

You wouldn't even look into it. You'd reject it outright. Or at least most would.

Again, it's the GIMP team's right to name it how they want. But the name is dumb, puts people off, stifles investment opportunity, and makes the whole project look like a joke at a cursory glance.