A personal trainer got COVID

I am genuinely curious to know what other people think here, so don't bash me please. Starting on a neutral ground. I was not in his shoes, so I am not judging at all. I am just a little scared.

So I attend personal training sessions at this gym. I wear a mask for the whole 1.5 hours I am at the gym. I don't judge those who don't wear one. My trainer wears it all the time.

He told me today that this other trainer was tested positive. He didn't quarantine himself for 2 weeks. He came to work and trained his clients while he still had it (he told my trainer he was still feeling sick). I was shocked to hear that and was immediately scared for everyone he came in contact with in the past 2 weeks.

I personally think it was irresponsible but maybe the guy needed money. The gym management was aware that he tested positive and still allowed him to enter the gym within 2 weeks of testing positive. Isn't it unfair? Just need some perspective here.

Posting anonymously as this is a little sensitive topic.