“proship” is an ideology that means “ship and let ship”.

It is the opposite of “antiship” which means “against shipping.”

Normal fans sometimes use the term to refer to themselves, to make it clear that they do not harass other fans over their ships, no matter what those ships are.

The pro-censorship fandom crowd misuses the term “proship” to refer to any type of ship that they personally deem objectionable.

Often this means that pro-censorship fans will refer to ships that they deem to be “abusive”, “incestuous”, “age gap” or “power imbalance” as proship.

What this means varies widely between the pro-censorship fan that you ask.

for example, many pro-censorship fans object to ships between characters who have an age gap of more than a year, characters who are separate races, characters who are enemies or rivals, characters who have known one another since childhood, characters who have called another character ‘brother’ or ‘sister’ in the past despite not being related, etc etc.