1. trump has not been inaugurated, and won't be for nearly 8 weeks.
2. Trump has attended 2 such briefings in the past 3 weeks (and possibly a 3rd, as the information I found is several days old).
3. VP-elect Pence has attended briefings daily. With inauguration 8 weeks away and an administration to staff, that's actually a very good use of available talent. This may augur Pence being utilized fairly more than has been common for VPs (it helps that Pence isn't a fool like Biden).
I'd say DU-folk are mountainizing a mole hill, but for their lack of a mole hill.