Donating Plasma and being on suboxone

yesterday I went to plasma center. I was there for 3 hours. I got through all the procedures almost until it came time to talk about medication. I was honest about being on subs and she asked me why I take them, she then told me they dont allow people with opiod dependence to donate and told me I had to leave. so my question is do they even test you for it when youre donating? im not a risk to infecting people. I haven't used a needle since 2019 and I have no desire to use. should I have just kept my mouth shut? I am always worried about testing positive for my meds so I am honest. the nurse was such a righteous bitch about it and you could tell she was happy to kick me out and use whatever little power she had around the place. can I go somewhere to donate and not tell them im on it?