Can’t the time sum of the transaction details returned by getBlockTemplate exceed 2000?

Summary: You don’t need to multiply anything. 20037 ≤ 80000 This is a valid comparison, so the returned value represents a valid block.

The confusion arises because there was an “old sigops” (pre segwit) where the limit was 20000. With the introduction of segwit in 2017, the meaning of sigops changed.

• The operations of the pre-SegWit input are each calculated as 4 times.
• Operations on post-segwit inputs each count as 1 sigop.
• The total limit is 80000.

The reported numbers are getblocktemplate RPC is a new time product with the appropriate 4x multiplication already applied to the relevant transaction inputs.

I would like to know if block mining is still considered valid in situations where SigOps exceeds the limit.

This would completely invalidate the block, but that’s not the case here.