There are lots of ways in which a new student can be irritating, most of which have nothing to do with the student's rate of progress.
* Refusal/inability to give real attacks, thereby making real technique nearly impossible.
* Refusal/inability to maintain connection after the initial attack.
* Refusal/inability to acknowledge one's own vulnerability, which manifests as refusing to fall down even when one is clearly in danger.
* Lack of understanding of appropriate ukemi generally. For instance, sometimes disconnecting after the initial attack is the right thing to do, but most beginners aren't able to make that judgment accurately.
With more advanced students, all these flaws can be addressed through atemi and henka waza, but most dojos frown on hitting and/or confusing beginners.
There are also a number of behaviors that are irritating in general, and even more so when demonstrated by junior students.
* Unsolicited advice, especially when that advice doesn't have much to do with what the recipient perceives as the problem or when the advice is seen as obvious, patronizing, or flat-out wrong.
* Taking ukemi in a way that renders the demonstrated technique impossible, whether through lack of understanding or deliberate obstructiveness.
(When these two manifest at the same time, it's especially annoying.)
* Preference for talking rather than training.
* Inflated opinion of one's own skill level.
I don't know you. I don't know which of these you are doing, but I've seen enough beginners to be pretty sure that you are doing at least some of them. Perhaps you could ask this person why he finds you so irritating? Or some of your dojo mates?
Generally speaking, there's a lot to be learned from training with people who you don't particularly like.
I agree; everyone you train with teaches you something new. Our dojo has a everyone-helps-everyone-else kind of policy, beginner or not. We all give each other feedback and advice. Thankfully, however, I just found out that this student is having trouble at college and is frustrated that he can't throw me. I'm just glad I know what's bothering him.