by Hermjard
I don't know if this is an English thing or not, but I see it as you rolled a heart so you have to use that as poison medicine instead of medicine for your wound as you would normally do. If you were allowed to do both with a heart, I would see the poison as separate from the healing since you get to heal as you normally would plus get rid of the poison.
If that would be true, the sentence could have easily been:
"Hearts you used to remove counters, cannot be used for another type of healing.".
or
"Hearts you used to remove counters, cannot be used for healing life.".
This is not the case. So I cannot believe your argument.