Poor Mikado. Once I'd read the OP I was laying bets how long until the "PFB" was brought out!
I am with all those who think your CM sounds fine, and that you don't need to worry about different approaches. And whilst I get where you're coming from with the word silly, I don't think it's going to do him any damage at all in feeling that HIS feelings aren't valid.
All that said, I'm going to defend your approach too though 
I'm the proud owner of a PFB. And wasn't able to have another (damn you PCOS and damn you cheating XH!) so I've had the fun of not having to address my approach when a second child makes demands.
On the specific incident of being told they can have a toy when they get home... At 2.5 my daughter would be happy with that AND remember it. And even if she didn't, it's a good distraction. I totally agree that rewards and punishments should be kept in time with behaviour, but I think it's fine to say "you can have it later" when it's a fact to reassure, not punish or reward.
I have had the time to "wait out" tantrums - or rather, talk them through. Although sometimes the storm has to pass first! All children are different and I got lucky with a mostly calm, accepting one. I'll go through hell with a teenager I expect, we all get it sometime!
I do think that my parenting is calm and that helps. BUT - maybe that's 1%. 95% of her calmness is luck. 4% is not having the trigger of a sibling 
I think the OP and I have had a similar approach with tantrums. They were few and far between for us, and at 6 years old now, she understands and accepts boundaries and is polite and well behaved.
So much comes down to the child you have. I just wanted to be a voice saying that what some see as wishy washy hippy drippy parenting actual DOESN'T always lead to the disintegration of civilisation, one child at a time 