Do you object to a baby/toddler getting wiggles out by walking up and down the aisle? They're behind you; would you prefer they get their wiggles out by banging on your seat? When we fly with our toddler (our three year old has flown only trip, but our older kid had flown more than a dozen trips [easily 50 flights, many of them intercontinental] by age three), we actively encourage them to get wiggles out by going up and down the aisle. I haven't seen anything in your description that I would consider age-inappropriate behaviour by the toddler or the parents.

Honestly, this seems like "tell me you've never flown with a toddler without telling me you've never flown with a toddler."

(Separate point unrelated to toddlers: I know FlyerTalkers consider passengers at the front of coach using the nearest lav to be a horrible faux pas, but I don't think it would even occur to the vast majority of travellers — my partner certainly in that group — that using the nearest lav is a problem.)