Silent and Flight mode on long pressing power button

These options are available from the indicators when locked by default, unless the setting to disable them has been used.
Are you asking to show them even when other access is disabled?

Yeah, sorry, I forgot about the quick settings from the lock screen option. The problem with it is that if the phone wakes up for some reason in your pocket then friction may mess things up.
In my case, I get frequent USSD pop ups when the data is on but the phone uses wi-fi and thus the screen turns on quite often too (a fix for bug #1373463 will come in handy). I had a few slightly unpleasant experiences, e.g. flight mode turned on by accident, volume slider changed position etc. So I disabled this feature long back.
Also there is a privacy concern as (at least parts of) incoming texts, Telegram messages, emails etc. can be read from the notifications indicator.
On the other hand, the probability of long pressing the power button by accident and selecting some unwanted option is very minimal I reckon. I have seen this feature present in android and firefox os too.