dnd 3.5e – "Share Spell" from the Druid Companion and Spells that block Extraordinary Skills

Yesterday my druid used Share Spell To trow Primary form (Compendium of Spells, P. 161) on his brown bear companion for harm reduction in the form of pleasant land.

But after rereading the spell, we started to have some doubts about whether that is really possible. Primary form state

You can not cast spells,
and you lose any spell, supernatural,
and extraordinary abilities of your
own form.

As Share Spell It's an extraordinary skill, I would not use it for Primary form it results immediately in Primary form being deactivated because Share Spell it removed?

This is to use the second paragraph of Share Spell (In addition, the druid can cast a spell with a "You" target on her animal companion (such as a tactile range spell) instead of on herself. A druid and her animal companion can share spells even if the spells do not normally affect creatures of the companion (animal) type.), but I think it applies to the first paragraph (having a spell affects both the druid and his companion) as well.

My DM allowed it yesterday and will allow it in the future, but RAW should be banned, the RAI is not sure. Is this interpretation correct?