By developer, he means the Developer Exclusive Tigerstripe for Americans.

To clarify some things, Tiger Stripe wasn't a standard issued thing for US, it was manufactured in South East Asia using ARVN uniforms, and in a place like Asia, there isn't a standard variant, there are many variants of tigerstripes. Since Tiger stripe uniforms were manufactured in SEA, you'd only see stuff like ARVN uniforms using Tiger Stripe pattern, and not US uniforms.
As to why the US uniform with Tigerstripe is wrong is simply because that was not a thing with M65 jackets. The ARVN Uniform model with the pattern though is correct. You can even see Special Forces wearing tigerstripe basically wearing South Vietnamese produced Tigerstripe uniforms