The problem isn’t the platform, it’s the rules committee. The platform is his excuse.
In the end...whatever influence Cruz exerts...it will have Zero impact on the outcome of the nomination or whom has the over-riding influence.
That will be the nominee, Donald Trump.
I actually hope Cruz can work to get some good conservative principle ideal to remain firmly in the platform...and most critically, that he and his people can work well with the Trump people to do so.
If that happens...it will be well worth it because working well together to get those types of things done tends to bring people together and let them learn some mutual respect.