Welcoming if they are offered is not the same as asking for it.
The only ones pushing this narrative of Russia asking/getting weapons from China are the same people and think tankies that have been itching for an excuse to fight with China and sanction it out since Obama's Pivot to Asia.
There are only two possible reasons why the Russians would refrain from asking for much needed assistance:
1. it is understood that the desired assistance will not be forthcoming and there is no point to the Russians embarrassing themselves by asking and be publicly refused.
2. It is understood there will be a political or material price for the needed assistance, either to be paid immediately or to be banked and drawn upon in the future, and the Russians deemed the price too high for the value of the assistance.