I haven't tested it specifically, but that should not, for the most part, be affected by this change. What's changing is the totem summon spells. Those are becoming actual spells and thus not usable while silenced/etc. The spells the TOTEM casts are something entirely different and separate.
They couldn't Spellsteal the Elemental, for instance, because it's "cast" by the Fire Elemental Totem; there's no buff on you to steal. They couldn't Spellsteal most effects for the same reason; it's being cast/used by the totem, and they don't have a totem to provide it. The one exception MIGHT be Stone Bulwark Totem, where the shield lasts 10 seconds without the totem, but they'd just get the initial shield, and even then I don't believe it's eligible.