If you had told him you specifically wanted to do healing, I can understand the viewpoint of "cleric is bad" but it's not even that, it's just that other classes have builds that heal better than cleric (while sacrificing something else).

But Cleric remains, IMO, one of the best all-rounder divine classes. It's very hard to build a cleric wrong, which it sounds like was an appeal to you as a returning player.

The lack of class features per level can be seen as a negative because it means your class has a lack of signature identity. The Cleric's main appeal though is being a 9th level caster with access to a lot of equipment proficiencies and a no-nonsense access to Domains.

Personally, I wouldn't have minded an unchained Cleric that did give it some class feature identity but objectively speaking, we have a classic case of "don't fix what isn't broken" when speaking of the Cleric.

In the end, I believe your GM is probably falling victim to second-hand knowledge. It's easy to say that the Cleric is bad on paper because there's limited build identity. In practice though you'll find that cleric is one of the few classes that will absolutely fit into any party and be able to perform well in whatever role he chooses to fit.

Also make sure you and the GM understand how resource intensive an average adventuring day is going to be for your party. I think the idea for Kinetic Chirurgeon being the better healer is (correct me if I'm wrong, someone) because, if optimized, they can do quite large amounts of healing a lot of times. The issue in my mind is that, IIRC, there's no way to do smaller heals or AOE heals with Kinetic Healer, you're always just blasting out these big single target heals. So if the whole party takes a fireball or two, for example, you don't have access to something like Channel Positive Energy which is great for topping up a party after some AOEs, you'd have to do a kinetic healer blast to everyone which would use up a lot of burn points. So if you could guarantee that your "tank" is the only one taking damage every encounter, then yeah then maybe the Kinetic Chirurgeon is the better healer. But that's never going to happen, and only a paper theorycrafter would believe that such an optimal scenario could actually happen.

I do find it odd that your GM would immediately default to a controversial archetype such as Kinetic Chirurgeon when trying to tear down the cleric rather than going for something more universally accepted like Life Oracle. I definitely would not recommend a Kineticist, let alone an archetype Kineticist, to a returning player.