Probably no point in stressing the girls by having him in the same exhibit until one of them is cycling. Maybe they are trying to better mimic natural conditions where they aren't around him until they are ready to breed.
Sorry my usually precise mind had a boo boo. I will change the name.
In reference to breeding... Tom is considered the more genetically valuable male. Sabi and Zohari are first generation AZA born rhinos. Their parents are imports. Tom also comes from more valuable bloodlines. The only reason Tony is at the zoo is because he and brother KC were fighting with each other at Granby and they didn't have the space to keep both guys separately anymore. It was easier for Toronto to send elderly female Shaboola to hang with KC while Tony came to Toronto. Tony can breed with the girls if Tom fails as breeding bull but the SSP definitely prefers Tom.
Sabi and Zohari just became old enough to breed last summer but it was just barely. No one held out great hope for a calf conceived in 2014. The odds are better that this summer might produce a calf now that the girls are older.