Sorry, bit confused! I can't accomplish this kind of strength via exercises..? Obviously I'm not planning to substitute exercises for dance practice, but surely exercises will complement the dance practice?
Well it's your choice - apparently you can be overweight & paunchy and still be a fantastic tango dancer, so why trouble yourself to get down the gym? Get back on the sofa and have another, er, cheezeburger.
Oh hang on, that only applies to males. Fat and unfit lady dancers are expunged from the records, but it's fine if you're a bloke.
I thought Tete's dancing was OK in an elderly kind of way and I'm sure he makes his partners feel great and has fab technique. I also like his air of relaxed, playful confidence. But things have moved on. All I could think about when I saw that video was how all his internal organs were spilling forward, uncontained by any kind of abdominal muscle tone and causing massive strain on his lower back, in all probability.
I would also not cite him as a good example of leading from the core - I think his lead is coming more from the chest. But what do I know, you haven't seen a video of me.
I agree that there are layers of muscle in the abdomen and that some exercises will only develop superficial layers. I also agree that over-development of the superficial layers is quite unnecessary for tango. But I think focussed and aware exercise will target any aspect of the body that you wish, and therefore would help Laelia to achieve her aims.
Most people don't do enough tango to achieve good physical fitness by that means alone - just look around any milonga. I think it's better to prepare for tango by getting fit first, and this would apply even more strongly to older dancers who have lost the natural fitness of youth.