No, this just means you don't understand the epistemology of science. We empirically evaluate--subject to uncertainty as with everything--subjective claims all the time.

Suppose someone has a huge gash on their arm and claims to be in extreme pain. Do you have direct access to their sensation of pain? Assuredly not. Do you doubt that they are in pain? Not likely--unless there is some reason to expect duplicity. Do scientists study pain, in order to devise more effective treatements? Absolutely.

So something went quite wrong with your reasoning here. Science can, of course, study subjective phenomena by using subjects as the measurement devices for themselves: you simply ask them about it.

Now you have a measurement--a somewhat noisy, unreliable measurement, but science has plenty of those and many statistical and experimental methods for compensating for that--and you're in business.

And if you reject this as a valid way to understand others, you end up with a radically solipsistic point of view.

So I think you need to improve your epistemological game before your argument can be taken seriously.