Toomes is specifically robbing Damage Control sites, and has been doing it successfully for 6 years or so, and in the finale he robs an Avengers supply plane. So I'd say there's definitely a motive to stick it to Tony there.
Tony could have tried and taken time to mentor the guy, been a little more sensitive to his feelings, you know...like a boss. I mean what a boss actually should do not the song-and-meme. He could have tried to have him work for SHIELD since Nick Fury has more experience working with dodgy assets with personality issues (since y'know Fury did work with and mentor Stark). Sure SHIELD was weakened after Winter Soldier, but Fury was still around right? There was a host of stuff he could have done, didn't do, and should have done. And above all, simply not take credit for an invention that's not his. That's something you shouldn't do to anyone.And what else was he supposed to do? Leave him in the company and risk endangering his employees?
But not by Tom Holland's Spider-Man is the point. In his own movies, with villains, and fellow Avengers team-mates, and in the eye of Nick Fury. But to reiterate...ultimately outside my feelings for Tony Stark and so on, that's not the real issue. It's not wrong for MCU Spider-Man to feature Iron Man and so on. That by itself isn't a problem. I just wish they did it better. I personally don't want to see a Spider-Man movie where a capitalist's irresponsibility and negligence creates problems and which ends with Spider-Man still seeing him uncritically as a good guy. I have a problem with a movie passing over in silence the fact that the guy who stole credit for another's invention is seen at the end as some kind of saint.The MCU has repeatedly shamed Tony for his past as an arms dealer or how he has dealt with women he has been involved with and blamed him for casualties in wars he didn’t start.
If they had used Tony Stark and Iron Man without those problematic elements then I would not have had so many issues.