We were on the island from May 15 - 22. I saw ribbons of sargassum as we approached SXM, and then in our flight over to SBH. This surprised me because there was no mention of it in this forum. On our first beach day on the 16th, it closed the right side of Saline. And on the 17th, Gouverneur was covered and thus nobody on the beach. We ended up at St Jean. So while it was around, it didn't have a major impact. There was always a beach to go to.
We did see one lone older man raking the sargassum on the far left side Saline beach, on the other side of the rocks. He only wore a hat, and seemed intent on his task.
Hope you always find a beach clear enough to enjoy!
Rob