I sometimes happen upon 15 minute conspiracy threads on twitter. Those people are just nuts - this seems to be the UK Qanon.
I listened to some of the podcast, but I just get dispirited and angry.
At very best those against 15 minute cities are simply defending their "right" to drive short distances and screw everyone else. They dress it up about "the poor" but those in the poorest income brackets are far less likely to drive and therefore would benefit from closer amenities. Or, the other staple which is "I live in Shitkicker, glos with only three houses and a pub - how can I walk to the local hospital 15 miles away?". No-one will implement 15 minute cities in your hamlet! The clue is in the name - CITIES.
At worst, it is just adding in another layer to feed the conspiracy loving morons who will shill for anything as long as gives them the attention they seem to crave. I mean it is technically possible that - say - a receptionist from Warrington has unearthed a global conspiracy by scrolling through Reddit during work-time, but if they had any self-awareness even they would have to admit it is unlikely.
There is a subsection of the 15 minute critics who clearly have absolutely no concept of living without a car, or that the amenities have been - since the 50's - designed around people who drive thus massively disadvantaging those who cannot. One argument I heard on the podcast was "what if the amenities aren't 15 minutes away". Well it won't be a 15 minute city then will it Einstein. And as for the argument that town planning was more democratic in the past - that is simply laughable.
Remember pre-internet that many pubs would have the permanently booze-soaked "character" perched at the end of the bar? You might say to them "nice weather" and this would be their cue to launch into their own brand of global conspiracy over clouds? Well social media has allowed every single one of them to meet up. Humanity is farked.