I think this is an XY problem. I suspect what you want to know are things like:
- What topics have you worked on and what papers have you and your group published?
- Where have students and postdocs that have worked in your group ended up?
- Do you have funding to take me on as a student?
- Do you collaborate with other groups and if so which groups?
- Can I talk to some of the students in your group?
These are totally reasonable questions, and you should feel free to ask them in a polite way.
There are a few issues with asking for a CV in your situation. The first is that the CV very likely contains much more information than you really want or need to know, such as
- What are all the talks this person has given at conferences?
- What are all the courses this person has taught?
- How much funding was achieved in every successful grant proposal?
- What is the list of every research visit this person has taken?
- What is the name and current job title of every student this person has ever advised?
Given how much information is in the CV of a tenured professor, it is a choice whether the person makes it publicly available or not. If the person has chosen not to post it online, they might be worried that giving the document to anyone who asks could very well result in someone spreading the document around. Additionally, keeping a CV up-to-date is a lot of work, and they might not feel comfortable giving you an out-of-date document and not have the time to update it. Finally, there is generally an expectation as a PhD student that you will do due diligence to find information that is publicly available on your own. Sending a request for a CV subtly implies that you did not try to do any research on your own. On the other hand, explaining that you have a question about $X$ specific piece of information and could not find it shows that you have done your homework.
Having said that, I don't think this matters enough that you should be worried about what they think about you. If your advisor is a reasonable person, they don't expect you to know all the unspoken rules in academia as a starting grad student. Professors are busy people, and there just are not enough spare cycles for them to think about the social skills of a prospective PhD student. They gave you the information you needed, just thank them and move on.
I also don't think this on its own is enough of a data point that you should be worried about them. You should try to find out if you will be able to work with this person successfully. Talking to students in their group, finding out where past students have ended up, asking your current mentors what they know about this school/group/advisor, and reflecting on the tone of the other interactions you have had with this person are good ways to do that. But, I don't think the email you are describing is so far out of the norm that it indicates that they are an unreasonable advisor. It doesn't indicate they are a reasonable advisor either -- this is just too small of an interaction to mean much of anything, and so I would recommend moving on. Certainly, I would not recommend making the decision to go to one school vs another, based on this interaction alone.