The current 2019 SSPX calendar lists Holy Days of Obligation as:
All Sundays - The Octave of the Nativity, The Ascension, The Assumption of the Blessed Virgin Mary, The Feast of All Saints, The Immaculate Conception, and Christmas Day.
This Thursday, The Ascension, the mass schedule is the same as it's been on all previous Ascension Thursday's, the same as a Sunday with all 6 masses scheduled. On the school calendar it is noted, "Thursday, May 30th: Ascension Thursday Holy Day of Obligation - NO Classes."
Yes, the SSPX priests consider Ascension Thursday a holy day of obligation and is to be celebrated on Thursday and they do expect everybody to attend mass on Thursday despite what the local district in Kansas says.