You saw what the UAE’s ambassador to the US said their goals for the future Syria were in 2016?
1. Secular with absolutely no religious influence on government
2. Minorities must be over represented in Parliament ie Sunnis are once again under the yolk of kuffar
3. No Islamist party should gain a majority in government whether moderate Ikhwanis or Salafi Jihadis like Jabhat Al Nusra
They're against "Islamists" for the same reason the Khaleej monarchies have hated Arab Nationalists and Left-Wingers. What those secular groups and Islamists have in common is that both tend to be against the Middle East's monarchies and have, since the days of Ibn Saud, encouraged the common folk of the Arab world to free themselves from the yolk of monarchy. Hell, they pretty much succeeded in places like Egypt and Iraq.
Jordan and the Khaleej States know that, long-term, there can be no reconciliation with these people who justifiably want them gone.
It's really gross to realize they've massively contributed to the destabilisation and destruction of many of the Greater Middle East's countries simply to greedily remain in power as royal families. Going so far as to aid Israel.