I’m with Costanza. I find it trickier to palm mute with an UWPS than with an DWPS even though I’ve had a life long preference for the upward slanting. With UWPS, I can palm mute lower strings strings fine, but palm muting the higher strings becomes anatomically impossible If I want to keep the upward slant. The reason being is that I like anchor the bottom of my palm above the lower strings, and I use my wrist for string tracking. To palm mute the higher strings, my hand position goes from a pronated to a more supinated position, which automatically turns my upward slant into an downward slant. The only way I could get around this is to string track with my forearm, which I’m not comfortable with.
I can palm mute what OP posted easily with DW pick slanting because all I have to is rest the side of my of my hand on the bridge, and just play it without having to move my entire hand up and down.