Can be seen as a positive or a negative:

You can still access your home country’s Netflix/streaming content. Log into websites that might geo-block (Homedepot.com blocks Europe…), log into work without security admins losing their mind about a “suspicious foreign access”.

Downside is that ads won’t localize into a language you don’t understand. I love it when that happens when travelling.

Actually with mobile roaming, I believe the implementation is that everything just gets tunneled back to your home carrier; so I think it is not so much the case that US carriers are deliberately discriminating Chinese traffic.

It doesn't have to be "disgusting on the part of the US telcos" to route Chinese SIMs through the Chinese Firewall if the other side of that agreement is that non-Chinese SIMs in China get to bypass that firewall.

Because ultimately, that means more ways to bypass that firewall. Chinese people in the US could but a US SIM to avoid the firewall. They could even take it home.

But routing Chinese SIMs through the firewall is only acceptable if the reverse is also true: letting non-Chinese SIMs in China bypass it. Otherwise it's just more censorship.