The main reasons for this may be these:
- Cecil's comrade Jericho (presumably his brother), the amle lion you ask about, got along well with Cecil. It was very probably that Jericho didn't hurt the cubs when he took over the pride, as it has happened. Also, relocating him would have left the females alone, and any rogue male could easily take over the pride. Jericho is an ally,so to speak, not an enemy for the cubs.
- Cecil's genetics. If they relocate the cubs, they had to raise them, and hence they would not be wild lions no more, avoiding to continue this good genetic pool in the wild.
- Although the risk of an alliance of rogue males taking over the pride is a fact, Jericho (probably 11 years) is doing a good job by now.
- Economy. I don't know whether there are parks with captive lions under the responsability of Zimbabwean authorities and/or conservation organizations, but the Zimbabwe is a country with low incomes that already told about that the cost of translocating these cubs is very high to them. Also, wildlife conservation doesn't interest the general media in this country, so there has not been a internal demand of soing it so.
But, so far, these cubs are ok:
If you want to trustable
information about these cubs, the best link is , it is the the team that monitored Cecil. In their web they report that the cubs are healthy and secure as of Aug. 18th 2015