I'm not sure precisely what you're asking. If you are asking about entering general discussions regarding ethnicities, then of course White people should be able to do that. I see nothing inherently exclusive about topics regarding race. However, if you are asking about entering discussions specifically referring to certain social factors and their effects on individual races, then my answer would be different. If you feel you have something to contribute, then, again, you should be able to. If you don't feel you have anything to contribute - I'm not sure if this is what you mean - then you can still join the discussion, but I personally would not recommend it.
Also, if you are afraid of running into people such as the example in the OP, I would recommend you rethink your priorities. You really should not be interested in conversing with people who lack a basic level of maturity. Of course, this would affect my answer to your overall question as well. If the person with whom you would like to have a discussion with is reasonable, then you should be fine talking to them about anything. If they are unreasonable, then you may have to be careful to avoid unwarranted backlash; but in that case, I would wonder why you are interested in them in the first place.







