I'm older than you, have taken more than one break, and have trained in more than one art.
You're not going to find TKD all that much different, in practice, to TSD. The forms will likely be different, in that TSD uses the turtle forms, which are not commonly used by TKD schools. But given that the Moo Duk Kwan (the source of TSD) was the largest of the original Kwan involved in the development of TKD, it's not surprising that there's a lot of overlap in the underlying principles.
You don't say where you are, but there are MDK schools all over the US. Depending on the history and lineage of their particular branch of the MDK, these schools may use the pinan, palgwae or taegeuk poomsae for colored belts.
Age of the instructor shouldn't be an issue. I learn from people a fraction of my age all the time.
As for the particular style of the dobak used... meh.... get over it, frankly. It's not a fashion show.
As for your age... forget it. You're just too old.
Kidding.
We recently promoted a woman to 1st Dan. She's 73. She used to bring her grandson to class, and when he lost interest (at 3rd geup, if memory serves) she kept coming. She was 65-ish when she took her first class.