They are linked because ultra-Orthodox coercion stems in large part from ultra-Orthodox control of key ministries in the Israeli government. Israeli prime ministers give the ultra-Orthodox control over these ministries in return for the Knesset votes that keep them in power.
And why must Israeli prime ministers include ultra-Orthodox parties in their governments? In large measure because they will not include Israel’s Arab parties. Israel’s Arab citizens (those within Israel’s 1967 borders) can vote and elect representatives to the Knesset. But by tradition, an Israeli government cannot rely on Arab parties to stay in power.
It must enjoy a Jewish majority in the Knesset. Some justify this tradition by noting that the political parties favored by Israeli Arabs are non-Zionist: they wish Israel were not a Jewish state. But, as it happens, some of the ultra-Orthodox parties that have sat in Israeli governments are non-Zionist too, since many ultra-Orthodox Jews believe that the creation of a Jewish state should await the messiah.