Lithium Thionyl Chloride are different chemical technology from Lithium/Iron Disulfide (standard AA/AAA lithium batteries) and "Contain toxic and corrosive liquid thionyl chloride", so since there is a lliquid inside, it may leak, just eating any seal that should prevent that.
Probably the issue is "just" in the wrong sealing as no pressure should happen like in alkalines.
Instead, as far I understand, Lithium/Iron Disulfide tecnology has no liquid inside, so no leak should/may occour.