Does a protestant become a quasi-Catholic by a valid protestant baptism? What is his status?
They would be catholic in the small c sense (i.e. part of the universal church), but not quasi-Catholic in the sense that they are sort of a Catholic, but just not there yet.
I see it this way. Babies are baptized Christian and brought up in the Catholic Faith. Babies have little knowledge about what they believe until taught. Protestants are Baptized at any time in their life and learn what they learn. They are Catholic and do not know it, recognize it, acknowledge it because they have not been taught so. They learn and profess what they learn and elements of Faith, Hope and Charity are seen in their journey. I believe that the OHCAC acknowledges this and sees it as real as do I. You will find that there are some Protestants that profess to be Catholic. OK.
I do not think that there is anything as a quasi-anything. Protestants are Christian, Catholic Christian by their Baptism. Protestants are whatever it is they profess by their learning. I suppose it would be fair to say that children that are Baptized and taught to be Catholic in the fullness of the Faith, have Faith formation and if that process is halted for whatever then they are not fully formed Catholic Christians. I would apply this to some Protestants in that they are not fully formed Catholic Christians.
Baptism is the rite of the universal Church that incorporates a person into the mystical Body of Christ.
In the broadest sense, baptism provides if anything, that sacramental, concrete connection with the universal Catholic Church. However, Protestants are outside the active and sacramental participation as members in the Church.
Subsequently, we see the Protestants as our separated brethren. Their baptism is considered as valid. If they decide to become Catholic, at the discretion of the Pastor, after proper instruction and affirmation, they could be attending Mass the next day as full fledged members.