You might be giving Trump too much credit here with regards to this move being an attempt to review and reduce wasteful government spending. This is just another move to force organizations to kowtow to him or be dissolved.

Totally agree with you on reducing the concentration of power in the executive branch though.

We're talking about a pause on all federal grants and loans, he's going to disrupt the economy and people's lives just to reduce spending to maybe more efficiently allocate funding. You bring up the number of programs for counter terrorism and railroad maintenance and safety, but they probably have different goals or jurisdictions. Not to say that they couldn't be merged or their spending audited, but Trump's method of just breaking everything and see what happens is dangerous and irresponsible.

Also the polls you bring up don't justify Trump's method here. Most people agree that some government spending is wasteful but that can't justify all actions Trump takes so long as he says it's for reducing government spending.