Not at all, they don't want to pay for Windows licenses, as seen there is very little incentive to actually support native Linux games.

Additionally they want to prevent losing Steam content to Windows Store or XBox PC App.

If they could get Windows source at zero cost, like the Netbook OEMs did in the early days, they would quickly forget about Linux.

Additionally, don't forget current Valve's management doesn't live forever like any of us, and who knows what will happen to Valve afterwards.