I don't think that to touch a unwilling person is a brawling roll, because there are other 2 spells with the touch range that does not require this, which is Sleep and Shatter, and both doesn't need a roll (besides the roll to cast it), and if it does it would severely nerf those 2 spells.
>>SLEEP
✦ Rank: 2
✦ Prerequisite: TREAT WOUND
✦ Requirement: Word
✦ Casting Time: Action
✦ Range: Touch
✦ Duration: Instant
The target of the spell must succeed with a WIL roll or fall
into a deep sleep for one stretch. NPCs roll against their
maximum WP if this is listed, reduced by 2 for each level
of the Focused heroic ability. If WP is not listed, NPCs roll
against 10. If the roll succeeds, the victim still gets Dazed.
The victim rolls with a boon at power level 1, normally at
power level 2, and with a bane at power level 3. A sleeping
person is very difficult to wake, but wakes up upon taking
damage. The spell can only be used on the living and has
no effect on monsters<<
Hm - I think touching the willing should be a free action, but I definitely wouldn't give a free action auto-hit vs an unwilling opponent in combat while spellcasting. So I guess IMC this will generally be restricted to out of combat use. It does make it weak, especially considering how powerful Ensnaring Roots is by contrast - 10m range & automatic success!
Another possibility for touch range spells vs unwilling would be an opposed check, say Brawling vs Evade, as part of the spellcasting.