ISIS and Al Qaeda currently operate freely on the Golan border with tacit approval from Israel.
It seems more likely that is why battle hardened pro-Assad troops are gathering in the area.
“It seems more likely that is why battle hardened pro-Assad troops are gathering in the area.”
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No not really. The Syria ‘rebel’ groups are more pro-Iran than pro-Assad, who, in any case, is a client of Iran. The majority of the other troops are Iranian al-Qods, and Hezbollah. Those groups you mention pose no threat to Israel as currently constituted. Israel would rather have them holding territory than Syrian SSA or Iranian troops, which together with their Russian Intel and air assets pose a historical existential threat. Suleimani does not care about the relatively small contingents of Sunni forces which are ill-coordinated, if at all, and without financial support from KSA.
Before invading Israel, the primary Iranian objective is establishing a route to the Med for Iran - a long held Iranian dream and, I believe, a direct order from the mullahs to Suleimani. Taking the Golan or at least neutralizing any Israel threat to that objective far outweighs any such concern about the few Sunni forces in the area - and which are being rapidly destroyed.
The route from Iran to the Med has only one potential threat and bottleneck: the Israeli held Golan. They are in the process of transferring 15,000 Asaib Ahl al-Haq troops to Lebanon to take up positions along the Lebanon-Israeli border from Metullah to Admit.