Rob said that you shouldn't use cl_pitchdown for angled bhops, no idea if it also applies to any other instances (like lvl 5 on exilenpals where you sync straight up). You can't restrict it unless you disable sv_cheats on the server which would also prevent the use of fullbright and other helpful stuff like that.
Now about the trick itself. I don't get why people think angled bhops are EASIER or even cheating. First you have to line up the angle perfectly, then you also need to not miss the bhop itself, while for downpogo you just shoot a wall. It's harder, yet faster way to do a wallpogo level with a bhop, BUT if you miss it more than once you are already loosing time (on like 95% of maps). Besides speedruns it also allows people who are not good at wallpogo to skip it. I personally use only walkshots (like walk right + shot -> bhop/bounce), unless the bhop saves like 30+ secs(without pitchdown obviously). And remember that we are talking about wallpogo on DEMO maps as SOLDIER. There are only 4 maps (at least that I know of) that are made for solly wallpogo and 2 of them you can't angle bhop at all (wallclimb and acepogo) and other 2 are way too hard anyway to have a big impact on times (attached and squared). And since demo maps don't have intended routes for solly, I don't see a problem. Or you can just make it so tempus wouldn't give points for demo maps as solly and solly maps as demo, only completion.
I took hardcore inspiration from hl2 speedrunning trick called save/load buffering (combined with damage boosting) when I came up with angled bhops. The intention was to make it so you can skip SOME really high wallpogos to save time, not to try and bhop every wallpogo level ever. Besides it made random bhops/bounces not as overpowered and lucky.
That's it, just wanted to say what I think about it as a jumping strat/trick.
Note: Using cl_pitchdown only saves about 3 to 5 secs compared to doing it with low sens and in no way can be compared to freezeglitching.