I'll bore people who have been here a while if I repeat my views on this. However....
I'm not sure that the CAS needs to do any more than it already does to "support Rugby". Most schools provide excellent facilities and coaching. What's missing in some schools is the player numbers. There are various reasons for that. One is the schools' catchment areas and groups. St Aloysius is the only academically selective CAS school: that, as the history of Grammar and Sydney Boys High demonstrates, erodes a Rugby program over time because it excludes a group of boys that each other school enrols (who are good at sport but ordinary in the classroom). That is a legitimate decision for the school to make: its duties are to the Jesuits who run the school, the parents and the boys, not to one sporting code. Trinity, on the other hand, has struggled for many years because its catchment area included large numbers of first and second generation migrant families (first Greek and Lebanese, now south Asian) with no cultural affinity for Rugby.
On top of that, every school now faces the problem that many parents are reluctant to allow their boys to play a sport perceived as dangerous. The risk has always been there (my mother didn't much like me playing), but it's worse now that significant mismatches exist within the CAS, in both skill and size. When there are 100-kilo boys running around in the under-16s, people are going to get hurt.
The only proper answer to this (as I keep saying) is to abandon (for Rugby) the old school groupings and arrange a three-tiered competition in which schools play against other schools with similar Rugby programs (measured primarily by numbers of teams, though other factors could be relevant). That way, your boy at St Aloysius can still thoroughly enjoy the game, competing against players of his own standard and level of commitment, instead of spending his Saturdays standing behind the posts waiting for another attempted conversion.