No. And I hope your buddy hasn't been constantly on gear for decades - as opposed to have done a lot of cycles over some time. On that basis so have I (16 years). Also at age 38.. anti-aging? You're not old yet ha ha
Regarding GH use. Like any tool it's a case of what it's being used for. the first place we look for science is how it's produced, in what amounts and for what purpose by the body. An example would be the growth spurt most of us had in our teens. I went from 5'7 to 6'3 between 14 and 18.
From memory (pls double check) the body pulses its GH release. It's not a constant thing. And, unless you're due a growth spurt (not at 38 eh) it's mostly at night now or following training. So, for example, tissue repair (as in at night) doesn't require you to be jabbing a pin in every 6 hours. Unlike Testosterone I can't see any additional benefit from keeping the body topped up through out the day.
As I said above 5iu's risks CTS. I went and looked at a bunch of online diaries of bodybuilders using the recommended 5iu a day and a large number complained of 'tight wrists'. Because GH can and does enhance growth of the connective tissue that includes the carpel tunnels (tubes around the tendons in your wrists). This grow and so squeeze on the tendons. In extreme cases they had to have the CT's cut.
If, as suggested, you did 5ius EOD (every other day) that's 3-4 times a week. It equates to 2.5ius a day with some of the 5ius a day benefits and lowers the risks of issues. It also means the GH last longer. On the colitis forums few were able to have the income to afford the $500 a month long term to get all the anti-aging and healing benefits. We can learn from them and their use (to heal their damaged guts) as much as we can from a 20isu a day or more for very short periods that Milos et al suggest.