Both the Greek wording and the Biblical record support this understanding. Obviously Peter operated under the influence of the holy spirit but he wasn't making decisions for heaven.
The problem is the abuse of this authority that could exist as exercised by the RCC, especially in the realm of giving its priests authority to forgive and remit sin, which means they (allegedly) have the power to keep people out of heaven and send them to hell, a power that no human being should ever be able to have or to exercise over a fellow human being.
"Power corrupts and absolute power corrupts absolutely* is not Scripture, but is true nevertheless. At least to this point, I've never seen it disproved.
Priests are not keeping anyone out of heaven. True contrition is required for absolution. Even if the penitent is wrongly denied absolution by the priest, the penitent can appeal to heaven.