We're getting push back from a third party (much larger company) over our decision to use OpenVPN to protect our AWS resources. Specifically, they're claiming that closed source is in general more secure than open source, a claim that is effectively addressed here. The consensus here and elsewhere seems to be that there's no advantage to either choice in general.
However, we're looking at a specific piece of software here, OpenVPN. Are there specific reasons why OpenVPN would be considered less secure than commercial VPN service alternatives?