I guess it depends, as the incentive structure differs. The VC is likely trying to squeeze some extra fees out for a different role he's fulfilling.

If I own 20% of a business worth $50m as a VC, and I run a $10m fund, then I will make 20% carry on the $10m exit. That's $2m in my personal pocket, pre-tax.

If I can facilitate a deal through a highly personal contact (i.e. close friend) where the company is sold to BigCo for $50m, and I can also charge 2% of the acquisition value to all investors (i.e. in line with what an investment bank or broker charges) then I pocket another $1m. So now I made $3m.

There is nothing inherently unethical about wearing two caps if you actually put a deal together -- whether that is raising capital (equity or debt) or facilitating something. Though in this case there MIGHT be a conflict of interest. But taking small percentage commissions is very common in business on certain transactions.