De Sa stepped side as the bottom-placed NFD club's mentor last week to focus on his managerial duties, with his former assistant Isaacs, 36, taking over the reins.
Umoya were last season known as Platinum Stars, but relocated from Phokeng and changed names after being relegated from the Absa Premiership.
De Sa says it was always the plan for him to relinquish the hotseat once the team settled in the Cape.
"Look, that was always the plan," De Sa tells KickOff.com.
"That was the initial plan when we were negotiating to bring the club to Cape Town. That was always the idea so it was just that we weren't too sure at the time ... about the workload. Ja, look it was always the idea, it was just put on hold for a while. That's it really, we just gotta go with what is best to continue. If I'm needed to be a kit man you know I will be the kit man. If I need to be the muthi man then I will be the muthi man. You can't do everything unfortunately, you can't be everywhere."
Asked if he would still consider coaching in the future, the former Bafana Bafana goalkeeper says: "I don't know hey, we'll see. Time will tell. You never say never. Let's see what happens. Like I said, never say never. Ja, you cannot predict tomorrow.
"Look, we know Dominic and we've watched him working in the last four months now so ... you know we saw him working and we know what he is about, so I don't think we need to have ... where are you going to get experience? You have to start somewhere. Look at a guy like myself, I came straight to a head coach role at Wits and I had never coached before. Benni McCarthy, he never coached before ... so you have to start somewhere you know. Everybody has to start somewhere. Sometimes people say you are taking a risk and sometimes people say it was the best decision ever."
De Sa says as is the norm in the NFD, Isaacs's contract will last until the end of the current campaign.
"In the NFD everybody is on a one-year with an option, so it's one plus one."
It didn't take long for Isaacs to show his quality on the bench as he managed to help the team qualify for the Nedbank Cup last-32 on the weekend.