Unfortunately, it is a latae sententiae excommunication. That one is hard to enforce. One whose excommunication is imposed upon him has a much easier time with enforcement (as the latae senteniae excommunicated person could assert that he didn't really understand 
that his action was forbidden)
The opinion provided was an "unofficial" opinion that this condition existed.
Had an official decree been issued, then the provisions of Canon 1331 would apply:
Can. 1331 §1. An excommunicated person is forbidden:1/ to have any ministerial participation in celebrating the sacrifice of the Eucharist or any other ceremonies of worship whatsoever;
2/ to celebrate the sacraments or sacramentals and to receive the sacraments;
3/ to exercise any ecclesiastical offices, ministries, or functions whatsoever or to place acts of governance.
§2. If the excommunication has been imposed or declared, the offender:
1/ who wishes to act against the prescript of §1, n. 1 must be prevented from doing so, or the liturgical action must be stopped unless a grave cause precludes this;
As I'm sure you can see, the imposed excommunication is FAR more serious.